closest thing to an efficient shapeshifter

hi everyone

I am afraid that my pure transmuter (see http://forum.baldursgate.com/discussion/31279/if-you-had-to-choose-only-1-magic-school/p2) will become painfully boring to play due to his very poor offensive capacities (no direct damage, shapeshifting damage is poor, especially with low thaco).

But i would like to push further the shapeshifter (NWN style) idea. I don't think the druid class allow that since the shapeshifter kit is limited to one form (boring...) and the avenger kit forms become weak at higher levels.

Therefore i was thinking of something like a kensai dualled to mage with the following restrictions :
- no armor (obvious from kensai)
- no weapon once he gets access to polymorph self (to prevent him from being a normal fighter)
- can only cast transmutation (and maybe abjuration. Still unsure) and sequencer spells (to prevent from being a "normal mage")

Does someone know which of the following work while shifted :
- kensai AC bonus?
- kensai THACO/damage bonus?
- single weapon, 2H weapon PIPs?
- extra APR from warrior levels?

I have read somewhere that if you dual wield before shifting, you get an extra APR. Is that correct? does it use dual wielding PIPS? can you use belm for extra cheese?

Any other ideas on ways to replicate the shapeshifter class for NWN?

Thanks in advance