You ask good questions and I'm happy to share my experience.
When I signed on, I joined the hospital group with the plan to assume my partner's patients once he retires. It's a good plan, but he's still really enjoying work and really just not ready yet. I was only seeing hs overflow when I joined on. I was barely seeing 12 a day. The group did advertise in the paper, but it really didn't amount to much.
I opened my practice to anybody and everybody. I didn't turn anyone away. You can Taylor yor practice to anyone but if your numbers aren't gong in the right direction, expect to be hounded by yor corporate overlords asking how they can 'help.' I'm nice to my patients (you'd be surprised how rare this can be), and they refer family and friends to me. I see a lot of hospital and er employees and they refer to me regularly. Getting in to see me doesn't take weeks. If someone calls me and really needs to get in, I generally can work them in that day. I have a good relationship with community specialists. My wife is the nurse of an orthopod in town. One of her colleagues wans to get an appointment with me and asked me today. I'm working her in on Friday at 11. That stuff really makes an impression.