1. Took about 45 mins I think. Didn't time it but it seemed roughly that. Definately under an hour.
2. 30 at a time.
3. They killed right (as in the right side of the screen) bottom 2, then right top 2 while also doing left top 2, then left bottom 2.
4. Yup. The reason being that I tend to AFK a lot. So I asked if they were doing a run that evening, they said yes, so I bought a VIP and went that evening - was less waiting around for me!