@burlesona, on your 2nd question:
For ST2 to be able to read a theme, it must be in the XML format you've been looking at. The reason to convert XML files to JSON is that it's less cumbersome to write. I use this plugin for the back-and-forth conversion: https://github.com/facelessuser/PlistJsonConverter
I think the Monokai theme that ships with ST2 is a pretty good place to start with as it's not too long and does not include a lot of syntax specific stuff.
Also, I find the following plugin very useful in picking out scopes:https://github.com/facelessuser/ScopeHunter
Edit: I've been working on putting together a theme from scratch. I'll see if I can clean up what I have and post it over the weekend.