First Focal Plane scopes have the reticle placed in front of the magnification lens in the scope. This means the reticle will grow and shrink as the magnification increases or decreases. Second Focal Plane scopes have the reticle placed behind the magnification in a scope. This means the reticle stays the same size as magnification increases or decreases. The reticle in a FFP scope is to scale as magnification increases or decreases making the holdovers marks accurate at any magnification. In a SFP scope the reticle is only to scale at the highest magnification making the holdover marks accurate only at the highest magnification. Either could be used for hunting at those distances, and it becomes a personal preference.
Yes, this Leupold VX-6HD 3-18x44mm Rifle Scope features a side focus adjustment to allow for fine tuning the parallax, making the reticle clearer and have less perceived movement when you're shooting at different distances.
I would use this Leupold 1 piece mount, but not sure how well it will work with your iron sights, they may need to be removed.
https://www.opticsplanet.com/leupold-177094-mark-ar-integral-mounting-system-1-pc-base-30mm-ring-combo-for.html
The Leupold VX-6HD 3-18x44mm Riflescope product code: LU-RS-VX6HD3-171565-KIT1 and LU-RS-VX6HD3-171568-KIT1 do come with flip lens protectors.
A good pair of rings would be (Code:LU-MT-LEUMO1-177138)
That has more to do with the shooter and rifle than the scope, the scope is capable of being used for 1000 yard shots.
This scope is second focal plane.