On your PC you can sort columns by clicking on the header. For example if you click on song , they are sorted in alphabetical order regardless of artist . If , as I do, you click on Artist then Artists in alphabetic order are shown , with their songs in alphabetical order . When you play the iPod you can similarly chose artist or songs. On the PC you can create playlists so , for example, at Christmas you could have carols or Christmas music . Playlists are shown on the I pad.
Not sure why the downloads are erratic- are you talking about purchases from Apple or elsewhere.