This site really got me started, but it's a tad out of date now:
http://knguyentu.com/wordpress/2009/...900-unleashed/
As far as a replacement interface, I would say Manilla 2D (also called TouchFlo 2d), SPB Mobile Shell 3 (NOT free though) or the new WM 6.5 interface called "Titanium". I believe there are ROMS with each of those three for you to try out in the "Upgrades" subforum.
Have fun!