Question about upgrades
 

Hi folks,

I just recently became a Delta Silver Medallion member and was curious about an upcoming flight.

Northwest LHR-SFO on 11/17 with a connection through DTW. It's my understanding that I can upgrade on domestic flights 1 day in advance if there are vacancies if I've read the documentation correctly. Am I in a position to upgrade the DTW-SFO flight even though it's technically booked as LHR-SFO? It's a T Coach fare if that matters.

Am I also allowed to priority board or that reserved for business class?

Thanks,
PJ

edit: I've honestly looked through delta's site for answers, but I find it a bit confusing making sense of what Medallion gets you.