Bluetooth Mic Stumper

This is a challenge I cannot figure out.

I'm a 4th geade teacher and am currently using my G4 15" for presentations and educational movies. We also use Interwrite pads to wirte on our projectors. I'd like to expand my use of the technology and start using the computer to project my voice through my external speakers (Logitec Z2300's). Obviously I need to be wireless.

I was wondering if I can play my voice in real time without recording it.

Secondly, I was wondering if a bluetooth headset can be used as a mic? Price is not really a factor, just please help me configure it if it can be done.

Thanks in advance.

I would not do it through your G4, I would get a wireless mic, and an amp. Some thing like this http://www.zzounds.com/item--NDYUHF3HM3