1) Monsters who are intellegent and have a treasure rating can use their treasure, as this is part of their CR. However, this treasure is THEIR treasure... you can't pool it.
2) Most monsters have a default set of scores already. For example, the entry for Aboleth reads "Abilities: Str 26, Dex 12, Con 20, Int 15, Wis 17, Cha 17" I'd prefer you use those for monsters. I mean... it's right there set for you. PCs units get standard point buy (or standard array, at your preference) because player races get most of their abilities from classes, and you can set their class to anything, and different classes need different stats. Monsters tend to have inherant power, and that power is preset to be geared towards certain stats... and again, the CR reflects that.
On the other hand, if you're using ECL and giving monsters PC classes, then they can have point buy as well.
3) Sure, I'll let you swap.
4) Summoning magic can be purchased. Since summons have limited duration, cost fantastic sums of money, can be dispelled, is castable by mages anyway which is factored into their CR not added to it, etc etc etc, I think that purchasing said items is fair.
5) I agree with Lazarus. You can have up to 2 higher levels of equipment. You can decrease your equipment as you will though.
6) Yes.
Allowed Sources:
3.5 SRD
Draconomicon (CRs modified to use UK's system)
Anything Else (Subject to Individual Approval after full disclosure to me)