i know that there are things you can alter in themevars but i am not sure whether they are theme specific.

Yes, they are. That's why its under the theme.

is it possible to move the icons on the desktop? currently they are stuck to the desktop and i'd like to catgorise them a bit. i'd also like them to be arranged neatly though like they currently are in rows and columns.

My guess is you'll need to change the desktop module from whatever it is now to xDesktop.

http://wiki.litestep.com