Out-of-towner with COVID questions

Depends on what part of town you are in. Here on the west side, nearly everyone is still masked indoors, even without any explicit requirements. I imagine that drops as you get to places with more tourists, but no one would bat an eye if you wore a mask and many indoor events will explicitly require it, even if the venue doesn’t.

Hiking: the Presidio has some nice trails or you could do the cross-town trail? Also you may like walking the filbert or Greenwich steps to coit tower. Personally, I think the best hikes are a very short drive away in Marin tho

Yes, people are mostly unmasked. Few restaurants require proof of vaccination/masking (more likely in western part of city)

If you're serious about the 10-15 miles, I would start at the waterfront, head up the Filbert Steps to Coit tower, make your way to GGB -> bluffs trail until it dumps you into Seacliff -> land's end, and then head into the richmond for food (probably should pick up something between Coit tower and the presidio for lunch if you're making a full day of it).

Some places are individually asking for vax cards but it’s not a city mandate. However, be careful. I caught COVID last week with a double booster and I can think of just one place I was indoors maskless that whole time.