I'm going to try to keep my reply focused but since you addressed a lot in your post I'll address what I can.
What did you do to your lower back? How tweeked? What type of pain? Like a "see the DR" type injury or something minor? Having had both types of injuries through the years I ask this question because putting the doctor off longer may not be the best COA.
6 hours of week is plenty of time. 2 hour sessions might be a little long but I'd rather have more time than too. 10-15 minutes of warmup (Greg has done several articles on this) and there is a plethora of good warmup stuff around the web. 1 example from Greg here: http://www.catalystathletics.com/art...articleID=127)
, either snatch or clean work and then accessories followed by mobility/stretching/recovery stuff maybe some conditioning (not meaning in a met con way, could be sprints or whatever)
With the info stated above it's hard to say. A good resource for self-education/self-torture is the mobility WOD just don't go overboard with it. There are over 400+ videos detailing different things, some things I think are a bit hokey but most of it is solid. He address squat depth in a lot of the videos.
Planning is good, sounds solid but 1st thing is first is getting coaching or attending a cert or something. I Oly'ed really poorly my first year+ coaching made a huge difference.
While your back is injured, something you can begin doing is take walks, i know it's not the most glamourous but it gets you on your feet, maybe throw in some mobility/flexibility stuff at the end.