1. Depends on what your SG is going to be about, but generally as much/little as you want to. Our group kinda burned out so we haven't done much in weeks. Same for the music group. Activity is very low across the board.
2. I'm not sure if you can transfer full ownership, but you can assign roles and have people help you manage the group.
3. I'm not the owner of our group, but I'm 99% sure the they can delete it.