Mac, not MAC.
Definitely run iTunes on the Mac side. Your Mac can read the NTFS drive, but you might want to back up all the music and reformat the drive as HFS+ so your iMac can write to it as well.
There are great Mac alternatives to Nero, including Toast. If I were you I would look for Mac alternatives to the applications you use in Windows, rather than dual booting or running a VM just to use these programs. You may find that the Mac versions are better in many ways then the Windows version, and run natively without all the overhead of a VM, or the time spent booting to a separate partition.