FFP vs 2FP in Burris and Vortex

It would depend on the type of shooting you are planning on doing. If you are having to calculate range you can do it with both types of scopes. Second focal plane requires it to be on the zoom setting that the reticle is calibrated for. First focal plane can be done at any zoom setting. Honestly I think it is a personal preference. As I am in the process of deciding what scope I am going to purchase I am leaning towards a second focal plane since the shooting I will be doing will be at known distances with no real ranging required.

FFP prevents accidentally using uncalibrated holdovers or ranging because the subtensions are independent of the power ring setting. The downside is the reticle can be tiny at low power and fat at high power. They both work but a good FFP reticle is a little faster and easier to use. How cluttered the reticle is is probably more critical for a lot of people.

Not necessarily. Some scopes could be a 4-16 range and be calibrated at 10 or 12, it would depend on the scope.