Here are a few more tips, having just converted, copied, etc from i-tunes:
1) i-tunes can convert most files to mp3, but not protected AAC (i-tunes downloads).
2)when you have i-tunes open and the list of songs in yoor library, right click on the grey bar betweenn the list of songs and the genre/album/artist list, if you ckilck on 'kind', it will show you what format your songs are in.
3) when you decide which songs you want (you can put then into a playlist as you pick and choose or selct and hold ctrl to select the next song etc), when you have finished selecting, right click on one of the selected tracks and copy, go to your SD card and select paste.
Hope this helps, it worked for me.