Justin -
Have been to Bandon three times, with the last trip in 2012. To answer your questions....
1. I have spent anywhere from 2 to 4 days on property.
2. I've never been off the property during the golf trip. The vibe is so cool on site I just cannot pull myself away to go see the Sheep Ranch or the town or the beach. I'm sure I'm missing out.
3. I booked all replay rounds prior to our arrival. I think you should see PD, BD, OM and BT twice each, mixing up the times you play them (ex: PD in the AM and then in the PM on a different day). This way you get to experience the courses, potentially, with different playing conditions.
4. A caddy will certainly help a golfer who is unfamiliar with the courses, especially with lines of play, where to hit it and where not to, etc. As I have become more familiar with the courses, I have decided not to take a caddy.
5. When making the reservation, you'll be asked if you and your group will need caddies, so, we booked our loopers in advance.
6. I walk 90% of my rounds and felt good after four days of 36. The walks are not overly demanding, with BT being the most strenuous. If you are doing the trip for the first time, with your buddies, I think 4 days on site is perfect. It is expensive, no doubt, but also very much worth it. There are few places I would rather be than Bandon.