Every location has issues, and asking exactly what grip gear you should consider is why you either have a key grip that bring his truck or you have the experience to know what is needed. Separation is the key here.
Separating the light designated for the green screen can be accomplished a 4×4 floppy for each 4×4 kino.
1.) How far should the Kino 4 Banks ideally be from the screen?
I would think 7-8 feet. I like to have the green screen at least a stop under the Key light.
2.) How many lamps would you recommend turning on for each 4 Bank from this distance to get the best green?
again only use what is needed 2-3 tubes per Kino.
3.) Do you think I would be better off using an Arri 150 or 300 for the backlight?
It doesn’t matter if you use a 6k HMI PAR as long as it is controlled to what looks right and not to hot.
4.) What type of gel or scrim should I look into for the backlight?
Some use a 1/4 -1/2 minus green magenta gel to help ensure the hair light is clean of green spill. I like a warm tonality, you need to understand where this image is going to be joined with. In most cases a nice warm back light is appropriate.
If this is your first green screen go slow and make sure you review your notes. Take time to use any light meter you may have and if possible look into the field monitor for help, as long as it is properly setup. If you see green on your subject turn out a few tubes on the green screen. No big deal. Have fun….
Good Luck
Michael Palmer