I am having a couple problems with syncing my iPod. First, all my music will sync to my iPod from iTunes but some artist, for example, Jimi Hendrix will be copied to and listed on my iPod more than once. They are the same songs and the same artist that is listed once on my iTunes but on my iPod the artist is listed about five times. The artist section on my ipod looks like this:

Jah Roots
Jedi Mind Tricks
Jimi Hendrix
Jimi Hendrix
Jimi Hendrix
Jimmy Cliff
John Holt
John Lennon

What can I do to fix this or what am I doing wrong?

Second, some , or most actually, of my movies will not sync to my iPod. When I sync it, I am prompted with a dialog box that says, "Some of the songs and videos in you iTunes Library, including "Blah blah blah", were not copied to the iPod "Blah Blah" because they cannot be played on this iPod.". What is the problem here? How do I get these videos on my iPod? A lot of the videos I have were downloaded via torrents so they were originally .Avi files when I got them, they I converted them to .mp4 or .m4v. Could this be the problem.

Im sorry if there is a thread about this already. I am new to this forum ad of five minutes ago so links to those thread would be great! Any help I can get would be appreciated. Thank you.