Start with FF chick starter and switch to FF grower on schedule. Having free-ranged birds, I think tractors are better.
I'm focusing on quail now, so someone else will have to answer #4 for you, but it should be around week 8-10, depending on how much you're counting on pasture for feed and if you're limiting them. Butcher at target weight.
Birds in tractors are confined and NOT free ranged. Certainly better than being in a stationary pen but.........a LONG way from free-range.