This idea of using a CDRW like a floppy is something of a fable as far as I see it. My opinions on CDRWs are well known on this forum and this is yet another example of them promising plenty, delivering nothing.
Why not create a folder on your hard drive for your MP3 files and save yourself the wailing and gnashing of teeth when your CDRW fails to deliver, yet again.
When you have a collection you want to keep, transfer to a CDR - these are so dead cheap anyway, it's hardly worth while messing around with the rewritable type.
Files written to CD/R or CD/RW are always read only. Files written to a CD/R cannot be deleted. However, "Powerdesk" which is a substitute for windows explorer (and much better) will delete read only files on a CD/RW (providing the CD was formatted), if it is an unformatted CD then the only way to delete files is by using the programme that burnt them to CD in the first place, eg. nero burn or easy CD creator. PoewerDesk is free and was last seen (by me) on PC Advisor cover disk for March 2001. I use it all the time now instead of windows explorer.