First, congrats for a great idea, and thanks for creating the thread. And here are the not-so-few things I wanted to add.
GENERAL WARNINGS FROM EXPERIENCE (rant, but useful)Playing a ghost character is a very cool, very rewarding, and a potentially maddening experience. Basically, it requires a lot of love from your DM.
By RAW (and indeed, common sense), you are effectively stuck with the equipment you had when you acquired the template, or at least when you begin the game with WBL. Yes, you can use any ghost touch armor/weapons you find along the way, and you can get the Ghostly Grasp feat as soon as possible. But non-Ghost Touch items (anything except weapons and armor) remain corporeal even with Ghostly Grasp. You can't travel through walls carrying them.
So, if the adventure isn't very very short, if you ever expect to level up and get better gear, your DM must be kind enough to provide treasure hand-picked for you, from ethereal opponents. Or introduce to the campaign a wondrous Ethereal Magick Shoppe. Or handwave the whole business and inexplicably upgrade your equipment every time you level up. Or houserule that Ghostly Grasp makes items incorporeal/ethereal as long as you carry them. If he refuses to do at least one of the above (and let's face it, he has every right), then frankly, you're screwed. You'll have to leave your new stuff behind every time you go ethereal/through the ceiling.
Apart from that, playing a ghost character can be very annoying, mainly because the rules of incorporeality / etherealness / manifestation are vague and ill-defined, and often just arbitrary. [No one had given them any serious thought before Spell Compendium and the Ghostform spell. That was when the designers first tried to understand how things work from the ghost's point of view. The rules that were eventually compiled in Rules Compendium are a huge improvement, but still nowhere near a comprehensive solution.]
The upshot is that, if you play a ghost PC, you'll need all sorts of ad hoc rulings from the DM, especially regarding manifestation: you are at the same time incorporeal for some purposes and ethereal for other purposes. You have no strength score and yet you DO have a strength score. It's silly at best, a headache at worst.
An example for "silly": what happens if you use an incorporeal touch attack against a corporeal opponent who Blinks? Do you add your str bonus or your dex bonus to your attack roll? Mechanically, there's an easy solution: Roll a 20% miss chance which does not apply, since you can both see and strike ethereal creatures. Use str for 1-20 which means he's on the ethereal plane at the time, or use dex for 21-100 which means he's on the material plane at the time. It doesn't make sense if you overthink it, but at least it works.
An example for "headache": what happens if an ethereal opponent successfully disarms you? Is that even possible? And if it is, your weapon (or other item you were holding) doesn't fall to the ground, because there's no gravity, but what happens to it exactly? Does it float in the air, in your square? Or does it fly towards a random direction until something stops it, like a ball thrown by an astronaut in space? And what if you weren't fully ethereal at the time, but manifested and incorporeal? By RAW, any item that leaves an incorporeal creature's grasp becomes corporeal. Oops. There goes your holy symbol. You can probably pick it up again because you have Ghostly Grasp, but it will never become ethereal again, so you can't go through walls with it any more. Bummer...
There just aren't any rules for things like that, and when there are, they are messy and conflicting. Things like that WILL come up. And you really need an understanding, cooperative DM.
Also note that you need to keep track of four separate conditions: ethereal, manifested vs corporeal foes, manifested vs ethereal foes and manifested Vs incorporeal foes on the material plane. Your AC and attack bonus will probably be completely different in each case.
By the way, when you are incorporeal, your armor bonus does NOT count Vs corporeal foes (barring force armor and the enhancement bonus of a ghost touch armor). Due to an obvious oversight (which I don't suggest you abuse, I'm just sayin'), shield bonus does count. [Source for this: PHB glossary. Just an example of how messed up the rules are, and scattered all over the place even after Rules Compendium....]
Being a ghost gets you a lot of defenses, but nearly all of them can be bypassed one way or another. Turn Undead is not the only thing you have to fear.
Feats like Awesome Smite, Ghost-Touch Spell and Transdimensional Spell can be a nasty surprise. Ghost-Touch is a +1 property and can be duplicated with a 3rd level spell. There's an Ectoplasmic Net that can catch you, a Ghost Shroud that makes all melee attacks affect you, and spells that range from annoying to devastating: Ectoplasmic Armor, Ectoplasmic Feedback, Corpse Candle, Ethereal Chamber, Ethereal Breath, Make Manifest, Incorporeal Nova (thankfully, 9 HD make you immune to this, yet another reason to prefer the Template Class over the DMG LA), Ghost Trap (no save, no SR. Basically, run.), Phantom Wolf/Bear, Black Blade of Disaster...
You fear all Force effects (Vortex of Teeth has no save) and all Abjuration effects. You are just as vulnerable to Dispel Magic (and Greater/Reaving Dispel etc) as any other character. In an Antimagic Field you aren't simply nerfed, you literally cease to exist. Finally, if you rely only on your undead type immunity to critical hits, rogues with a wand of Grave Strike or a Greater Truedeath Crystal can sneak attack you, and your hit points total is nothing to bask at, so beware the little guy.
Horrific Appearance has a niche, but very effective use, with a party of undead/constructs. It only affects living creatures, therefore your allies are safe from it (then again, so are enemy undead/constructs, so its effectiveness depends entirely on the campaign). It's not, however, unreasonable to ask your DM for a homebrew trinket that protects your living allies. If Evil, you can combine this ability with Hexblade (Dark Companion ACF) 4/Paladin of Tyranny 3 (or any other debuffer build, evil or not) for great synergy.
Draining Touch:Draining Touch (Su): Look closely at this ability. That's right, you add your strength modifier to your ability damage rolls for this against ethereal opponents. And you can hit any ability score you select. And ethereal in this case is referring to opponents who share a plane with you (since ghosts start off ethereal), so if you planeshift to the material plane and bulk up... can we say d4+stupid ability damage to your opponent's lowest stat? You can punch the stupid right into somebody.
I could allow that, because I understand the logic behind it. But the DM might very well say
"what's that now? no no dear, it says here specifically that against material opponents you don't add anything to damage, I don't care if you planeshifted". So, consult your DM first.
It's not mentioned here, but I feel it's important. It will be tempting to completely dump strength, since most of the time you won't need it. (Unless you go for the Plane Shift/Draining Touch combo above.) Avoid this. A ghost PC will inevitably bring ethereal opponents to the party. And Vs ethereal your str score exists and it counts, you use it for attacks (which can be ignored with Weapon Finesse) and grapple (which cannot, until you get constant Freedom of Movement from somewhere). Sure, str can be low, but if you go for, say, venerable halfling and end up with a Str of 1, the DM can make you regret it.
Quicken Manifestation (Libris Mortis): Manifest as a free action (becoming ethereal again is not affected.) If you intend to stay ethereal and out of reach most of the time, grab this one. With a debuffer/Horrific Appearance build, it can wreak havoc in enemy lines. Move in their midst, manifest as a free action, and a lot of things trigger automatically: Horrific Appearance, Aura of Despair and Dark Companion, for example. That may easily result in -8 to saves to at least a few opponents, and you still have a standard action to use as you please. If they can't detect you, you can use one round to move there, manifest at the beginning of the next round and surprise them. Or you can use it for hit-and-run tactics. The possibilities are endless.
Lifesense (Libris Mortis): Living creatures emit a light for your eyes only. This is one of the precious few ways to trump even Superior Invisibility and Darkstalker, so every undead character should consider it.
Improved Turn Resistance (Libris Mortis): This gives you a +4 Vs Turn/Rebuke, your most glaring weakness.
Flyby Attack is always useful for flying characters.
Empowered Ability Damage (Libris Mortis) is not bad if you go the debuffing route.
Prefer Eternal Wands (MIC) over normal wands, because charges get used up, and any new wands you buy won't go through walls with you, even if you can actually hold them.
You fear force effects. If you want to avoid the humiliation of dying from Magic Missile, buy an Eternal Wand of Shiled, and/or a humble Brooch of Shielding (DMG, 1500 gp). This becomes non-functional eventually, so buy several, they're quite cheap.
Definitely get some way to teleport out of Force traps: buy an Anklet of Translocation (MIC, 1400 gp, swift action teleport 10 ft, 2/day), Boots of Big Stepping (MIC, 6000 gp, standard action teleport 60 ft, 3/day), something.
A Veil of Allure (MIC, 14000 gp) gives +2 DC to all your Supernatural Cha-based abilities, i.e. your ghost special attacks.
A Cloak of Turn Resistance (LM, 11000 gp) gives you another +4 Vs Turn/Rebuke, your most glaring weakness.
The Ghost Touch weapon property can be easily and cheaply acquired with a Lesser Truedeath Crystal (MIC, 5000 gp).
Ring of X-Ray Vision (DMG, 25000 gp): For scouting missions and a safe retreat. There's only one thing sneakier than a sneaky ghost, and that's a sneaky ghost inside the wall or ground, looking out. Buy this, and laugh at people who can see ethereal. The only thing that can now reveal your position is Mindsight (or see ethereal and the exact same ring, obviously). Beware of the small, 20 ft range, though.
Frankly, I believe that using the suggested feats will not fly with most DMs, even if RAW allows it, which I doubt a bit. (This isn't Theoretical Optimization, it's a Handbook, so I figure what may happen in an actual game is important. In actual games, RAW doesn't trump everything. The DM does.)
These feats apply to types like humanoid (elf). Becoming a ghost means you're Undead (augmented humanoid) and not an elf at all. Again, I could be wrong: I'm not sure about RAW because I don't know what's the deal with conflicting races and types, but RAI is obvious here.
Even if you follow RAW (?) blindly, losing the Undead type means losing everything that comes with it. You can't conveniently say "oh, I'll keep my immunities and d12 HD since I'm still dead and all, but you can't turn/rebuke me any more, mwahaha." Who would say that? And what sort of DM would accept that?
As for getting rid of the Undead type by stacking other templates on top of it, that's out, too. Even if you find somewhere an ill-thought template that could be legally applied to ghosts and change their type, there's a Savage Species rule on template stacking which overrides it: once you gain the undead type, you can't change it with a template.
...Realistically, I'd say you're stuck with Undead for good. The best you can do is get a feat and an item for a total +8 Vs Turn/Rebuke (+12 if you took 4 levels of the Ghost Template Class, which you probably did), and hope.
