Bitrate 41000hz or 128kb is best or 192kbs both sounds great.
160kbs don't sound great and over 192kb is to high for sound,there be no bass just hard on ears so make sure you download mp3s 128/192kbs or use tool to covert them.
The skip could be the music file check it out may not be itunes, problem fixed if it was just the mp3 file.
If not then this be first I seen post about itunes burning music and skips under v7.