That's a good map -- that is, it's readable. And it shows Richmond as 7a.
I'm sure all the things I am investigating will make themselves known here. Probably not all in this thread, though.
And yes, composting is the first thing I do in any new garden, pretty much. Get that set up and then I feel I can operate.
PS HA! I checked the updated map and it looks like it splits Richmond into two thirds 7a, one third 7b. In any case, it's right on the boundary, and since I am in the northern part, I would still be 7a according to that.