let's say im recording a cd to the hard disk and shut off the car half way through... what happens? will it pick up where it left off when i start the car again? will the track it was recording be corrupt?

It will pick up where it left off, no worries

thanks! 1 more question regarding recording - if i make a dvd audio disc will it record? will it even play? i know it won't play mp3's off of a dvd, but what about dvd-audio?

No it won't