Well.. I'll offer and opinion. I don't know what you mean by a choosable list, but I prefer where there are a few main buttons on the main page, allowing selection of catagory. Its nice to have a branded main page, but not nessecary.
On the mp3 section, I prefer fewer upcoming songs listed, and larger control buttons/current song info. Think IPod... the song selection should be a seperate dialog if possible.
Skinning is one of the hardest parts in my opinion. There is basic skin function, where you are simply changing the graphical appearance, yet buttons stay in the same position/size/function. I havn't figured out with QT an easy way to customize position/size/function of widgets. I'm sure it could be done... but it doesn't seem like it would be easy.