I think T.King is in progress of making skins for eq2 by the looks of the new download section here , or maybe even a UI ... but I may be wrong lol
Learn PS with with somthing easy like a default .dds file
Also SoE's xml is not true xml (if true xml even exists lol) its there own version of it so to speak to start of with somthing like the player window and work from there mate ... also learn to use the UI builder its a real pain at 1st but once you get to know it the same beast is actualy a god send and means you dont hav eto spent as much time looking at pure code
GL