Hey man, I am starting a similar project, will be interested to follow your progress, if you post how things go.

I can't answer all your questions, but a few thoughts popped into my head:

1. A friend swears by the Shimano UN55 BB, I recently bought one off eBay for $20-something, expect it to last forever.

2. Reading up on retroshift for my build, I recently came across this statement, "V-Brakes ... offer exceptional stopping power and have long since replaced cantilever brakes on Mountain bikes. ‘Cross bikes have only kept with cantilever’s as road brake/shift levers have not had the correct pull ratio to allow them to use these more powerful brakes." So it would make sense that road brifters should all work equally well with calipers or cantis.

3. I have ordered my crosscheck frame, it's riding in a UPS truck as I type, and it is supposed to have a Surly seatpost clamp with it. Don't know if you wanted a Thompson-specific clamp for some reason. Or maybe you're getting a used frame that might not have the standard little parts included.

4. I don't believe in organic food, "high quality" speaker or hdmi cables, or boutique cable housing. Just dribble some light chain oil into the housing before you run the cable through, and you should be good with whatever your bike shop sells you if you just hold your hands out and say "I need this much cable housing".

6. Like you, I am also planning on Tektro CR720 cantis, and every new kit I've seen includes straddle wires, triangles, pads. My frame is also supposed to come with a Surly brake hanger, which if I understand correctly, will hang from the seat post clamp and provide a cable stop for the rear brake. This thing. Don't know if I'll have to buy a headset hanger for the front.