MP3 CDs

[elendil]

A couple of questions:

1)When I burn an MP3 CD is it strictly necessary to finalise it? The reason I
ask is that I see lots of car radio/CD/MP3 players that can also play CD-RW media. What's going on?

2) Can I have multiple directories on an MP3 CD? Will the player automatically start going through the subdirectories when it plays?

Thanks