[Amelandbor]

Just try the different builds. Personally I would always go for OpenElec when you strictly want to use xbmc, it's fast, easy to setup and small. If you however want to use your htpc for more than only xbmc, then you could always try something else.

OpenElec has the option to add files just by copying them to the samba shares through your home network. And I guess it can also be done by a USB pen.