fred, he hasn't modified eePanels at all. Just take the textures (from both places) and follow the instructions given on the WLK page. Or add the textures to SharedMedia through MyMedia and use them from there.
If I'm not mistaken, the above UI linked is mirrored hence its identical, and therefore I could lower the RAM-usage by using the same data twice but mirroring the display on it. I want to keep the UI as small as possible, so I'm wondering if there's any way of doing that in eePanels2?
No, that texture (if you mean the bottom panel in each screenshot) is not a mirror image. It's most definately one whole texture that spans the bottom of the screen.
@kaych: don't repost your question. It's still on the same page even. /sigh Though it has been almost a week. Do your action bars hide until mouseover? Parent the panel to one of them. But without some extensive hooking and scripting, you cannot make your bars and Autobar hide/show based on whether or not your mouse is over the eePanel.