Best way to burn I-Tunes/Mac

I have a G-4 Mac with I-Tunes, dial-up, external cd burner.
What is the best settings for:

Import:
MP3 or AIFF?? ( or another setting?)

Streaming Buffer:
what size? Small, Medium, or large?
Whenever I try to download the 30 second preview of a song it loses the stream about every four seconds.

Burning:
Preferred speed?

Disc Format:
Audio or MP3?

Thank you in advance if anyone has any experience with the Mac and burning cd's.