software to rip multiple cds at once

ive got a mac with multiple internal and external drives and i want to rip my cds ive got about 2000 so anything to speed up the process is good
is there any software that can rip cds from multiple drives at the same time
also whats the fastest format to encode them (.mp3 .aac etc.) or is there a way to rip them without the encode and i can do that later
i dont mind having the computer chug away to (re)convert them later if it means they rip faster

thanks