How do you do the mixing if a person is not in town, do I have to fly there, or do you just need a studio recording of my vocals?

Both ways work... most of our customers do have separate studios they'll record from and just send us the audio files of the session, but some with a higher budget will work physically with us and come in from out of town (Custom Production level 5 and higher...more details here - https://sfrbeats.com/pricing?q=Custom+Production).  Everyone has a different way of working they prefer.. and we cater to both.