need help

I haf a bunch of questions for this map i'm making, can anyone help? thanks.

A. Is it possible to make players unlearn upgrades? I'm trying to make an rpg that requires your character to equip weapon items to be able to attack.
B. And how is there a simple way to limit the amount of a certain item class in a heroes inventory? (ie. Only 1 permanent item allowed.)
C. Last but not least...er....wut was it again? oh yea, can you, using triggers or anything change a unit's model without changing the unit??
D. Can you make a 3rd person view camera that always shows the character's back?

A. It is impossible to unlearn upgrades. The best minds have thought on it, and the answer is still no. Sorry.

B. There isn't a simpler way. You can use a complex method, and looking at DT4 is a good way to start. You can find it here.

C. Sorry. You can't do that.

D. Yep, thats possible. Draco's (and others) camera works well, and will show you how it's done. Find it here.

thanks, yea i found a reallly long way of limiting items and such but it was finished in 10 mins meaning it was buggy like hell...and yea thanks ...i'm planning on making my rpg a multiplayer thingy....if possibly a mmorpg that includes item forging, chat commands to talk to villagers, food/cooking, date and time and a bunch of other ****

so yea....if i ever do end up finish you'll be able to play it (if ne1 decides to) in a year or so.

oh yea....one more
A. how can i make a trigger that starts when two events occur? (can't think of anything so yea)