I don't know the terrain your in, but for me I move a lot when I hunt. That could be glassing an alpine bowl in the morning and bushwhacking through a swamp or thicket in the evening.
I cannot stand having two guns, and I cannot stand being a one dimensional shooter. If selecting scope and rifle combo I limit myself to 800 yards (as to 1000+) but I open up the effectiveness at close range I am happy to drop the 200 yards of effective range (OK, I'm not happy, but you get the point
I would go for the Nightforce if you have the coin, but if your worried about weight leupold mark 4 are nice, any of the swaros or ziess's and I personally really like the Vortex. Bushnell has a very high magnification range but I don't know about overall quality and I wont buy a scope without matching turret/reticle.
As for magnification range I would say that your right on with the 4 on the low end and 14 or higher on the high side. You can go more than 14 but no more than 18 unless you get a March that has a very good bottom end.
I have a 2.5-10x44 that I love, but it would be nice to have a bit more magnification after 600 yards.
as for 7mm bullets, 160 AB or 180 berger.