1. If there are DRM files that you're trying to transfer (such as mp4s from iTunes), they wouldn't play on your handheld anyway. Are you trying to transfer DRM-locked music? Also, if there's insufficient space, there's insufficient space. Pull the battery to do a hard reset and that should free up a bit of memory.
2. To be clear, you need a BLACKBERRY DATA PLAN to access anything data related. E-mail, Internet, etc.