I've read plenty of forum posts but I'm finding myself a bit overwhelmed, so I'll list out some specific questions. Sorry if these have been answered elsewhere!
1. ROMS: From what I understand, this changes many general functions and functionality of your phone. Is there a way to download multiple and switch between them, or is it a one-at-a-time thing? Does it matter whether you install a ROM before a theme or vice versa?
2. Themes: I believe these are app icons/docks/possibly wallpapers. Can you install any theme you want over any ROM you have? Is there a way to have multiple themes available and easily "switch" between them?
3. Kernels: From what I understand, kernels change how your CPU operates...getting to be pretty serious business here. There are so many kernels released...what types of differences do various kernels offer?
Though I have no problem following instructions to root my Droid (I recently did), I don't know what each step is accomplishing. When I used the DarkEdge (theme/ROM?), I ended up having ROM Manager, BusyBox, DarkEdge Tools, MetaMorph and maybe some other stuff; eventually, I became glued to the instructions without a real understanding of WHAT was happening and how these processes work with other ROMs/themes/whatever.