Upgrading "H" Fare on Domestic - What is Required

Just booked an upcoming flight on DL 61 (SFO-ATL) with the lie flats on an H Fare. I usually just wait for the complementary Medallion Upgrades, but I'd like to go ahead and use miles to get an F seat since I'm down from PM to GM.

- What is the process?
- What fare bucket is required on DL 61 to process the upgrade?
- What if I SDC on the day of the flight, do I get my miles back?

Thanks!