For the second question, you can split wave files in Audacity using labels (Ctrl+b) and "File->Export multiple". More detailed explanations are available by googling. Try to split the files in an area of silence and then edit to fade out to the break or to fade into the music. You'll probably need to rename the files once they're split.
Audacity's noise removal effect is reasonable, just don't expect it to be perfect. The best thing for hum is to not record it. That's from experience working with high end equipment and software and from many hours chasing ground loops, transformer hums, flourescent light buzzes and recording single coil guitar pickups. Sometimes what's annoying hum to you now is not noticed at all later.
Audacity's wiki has a lot of good information. Check:
Noise Removal - Audacity Wiki
and
Transferring tapes and records to computer or CD - Audacity Wiki