(1) At SFO they board anywhere from 45 to 30 minutes before departure and I think the same goes for MSP. It also depends on how full the flights are.

(2) Unless you are the very last person to board the first class cabin, then you shouldn't have a problem. Actually I've never had a problem in row 1 except for the times that I have been late for a connection and I'm almost the last person on the plane, then I've noticed that the first class bins will fill with coach people's stuff.