With a 6 strength you'll definitely want the mithril chain shirt instead of a breastplate. That extra AC would be nice, but ideally you won't be getting hit in the first place. Note that
mithril shirts are actually 10 pounds, meaning it'd be 5 pounds for a small character.
The
haversack allows retrieving any item from the large central portion as a move action that doesn't provoke AoOs. All told the haversack can hold 120 pounds of stuff or 12 cubic feet and weighs 5 pounds.
A
type 1 bag of holding can hold 250 pounds or 30 cubic feet, but it weighs 15 pounds (which is absurd in my eyes). It also costs 2500g which isn't likely to be in your price range, is it?
Note that, strictly speaking, it doesn't say that magic items change their weights,
only their sizes. But it would be reasonable to rule that their weights change for the character. What those weights will change to could be a bit hard to figure out since the
adventuring gear section says backpacks and such made for small characters weigh 1/4 as much, but stuff like
weapons are half instead.
Given the costs and weights, the haversack would be much better if you do indeed need the storage. If its weight goes down to 1.25 pounds without changing its holding capability then that's pretty good. The bag of holding would still be 3.75 pounds and 2500g so it wouldn't really let you do other things.
Yes, you will need a spell component pouch since the beguiler does have a few spells with material components and can get more through Advanced Learning. For cantrips
this list shows that Daze and Ghost Sound require materials while for
1st level spells it's Color Spray, Comprehend Languages, and Sleep that need materials.
2nd level shows that Glitterdust, Hypnotic Pattern, Invisibility, See Invisibility, and Spider Climb all require material components too. If you're going to use those spells (and you definitely want to with some of them like Daze) then you'll either need the spell component pouch or the feat
Eschew Materials.
