OT, again!!!: GarageBand question

[gooddog at interlync.com]

Folks;

I attend a tai chi class where our instructor discusses/lectures 
frequently. It occurred to me I can record this using GarageBand and a 
microphone with my 500 mhz dual usb iBook.  However, I'm not sure of a 
number of things:

A) what format to save it to in order to burn a cd.

B) What size of file will it be if it's an hour and a half to two hour 
talk

C) Is it workable to record such a length of audio and not completely 
bog down the system?  I'm not looking for professional quality, though 
this would be great if it were possible, if this will be an impediment 
to the system. "Good enough" will be good enough.

Most important, since my hard drive is only 10 gb, can I install GB on 
my 15 gb iPod and run it off of there (connected to the iBook, of 
course)?

Thanks in advance.

Mark