not sure about xbox but with an xbox 360 you can plug your music device in the back with a usb cord. Not sure if it is iPod only because that is the only thing i have tried it with but I don't see why it wouldn't work with any other mp3
I am almost positive that a 360 can rip Audio CD's, so yes. I personally prefer to just play my mp3 player through a 360. You can also play mp3s through an external hard drive plugged into it, which is usually a better bet than playing actual mp3s off of the 360.
Ive tried transferring mp3s from my phones memory card to the 360, and no go. It will definitely rip cds, however.
I've been playing my music from an External hard drive into the 360 but it's annoying. LOL Why have a hard drive on when I have a 360 hard drive. Oh well... I'm not at home so I won't be able to try until later tonight.
It can be done, but I prefer to stream mine from my mainbox. Frees up 360 HDD space for Rock Band tracks, you see.
I don't have a 360, but my PS3 rips CDs onto the HDD, so I don't see why you can't do the same thing on 360, especially since you can have custom soundtracks for your games.