As for UMD crossbowman...
Crossbows get a bad rap. It's more feat heavy and less DPS than a bow, but crossbow has some advantages, like less MAD (no need for str at all), better crit range (critical feats work on ranged attacks), and ability to shoot while prone. Starting at level 9, you wouldn't have to deal with the avalanche of feats required.
That said..the crossbowman fighter archetype SUCKS and is a TRAP. Your best bet for crossbows is to be a ranger (early feat entry, spells, and nice skills) or some class with sneak attack (for more dakka). Vanilla Fighter, Mobile Fighter, and anything else that basically lets you keep weapon training w/ a crossbow is decent if not optimal.
The crossbow archetype is complete balls, unless you know you'll face tons of casters without wind wall. And even then you're probably better off delaying or readying without spending feats on making that better.
Tomasso the Arcano Crossbow Engineer is a rejected student of a random wizard academy:
Human
str 11
dex 20 (24 with item)
con 14
int 12
wis 12
cha 14
feats
h1 Point-Blank Shot
1 Crossbow Mastery
3 Weapon Focus
5 Combat Reflexes (1+dex AoO's/round)
7 Snap Shot (5f threaten)
9 Improved Snap Shot (15f threaten)
f1 Rapid-Shot
f2 Rapid Reload
f4 Weapon Specialization
f6 Precise Shot
f8 Improved critical
future feats: improved precise shot, clustered shots, master craftsman (+2 craft, can make magical weapons)
I took the trait to get UMD and a +1 on it and always keep a wand of Gravity Bow at the ready. I took craft:weapons (for crossbows) as flavor and intent to play him as an 'arcano crossbow engineer'.
AC = 10+9breastplate+7dex=26 (mithril breastplate +3 together with armor training means +7 dex and no check penalty)
ATT = 9+7dex+1wpnfcs+2mastery+1pbshot+1mgc = 21/16 OR 19/19/14 OR 16/16/11 deadly aim.
DMG = 1D10(OR2D8gravitybow)+2spec+2mastery+1mgc+1pbshot+6daim = 1D10+1D6+12
17-20 crit / 15f threaten, can AoO when flat-footed.
I know the bow is 'better', but obviously I'm going for flavor by picking crossbow. My DM rules that shooting a crossbow doesn't draw an AoO, but reloading does. So crossbow mastery fixes that which saves me from picking up Point Blank Mastery. It's nothing spectacular, but it does the trick. I'm tempted to take Skill Focus UMD, because it would take me to +18, meaning anything but a 1 works. Next level it will bump my UMD to +22 so I can always use a wand without failure and up to CL3 scrolls. I'd probably drop Combat Reflexes for it and take that at lvl10 instead.