Same applies to Leafeon & Mossy Rock.
Yes, it will. As long as the Pokemon is leveled up—and it doesnt matter how you do it, as long as you do—in the same area as the rock, then it will evolve.
Source: That's how I evolve my Eevees into Glacon/Leafeon, in fact
Yes it will.
Source, I did it xD
Yes you can.
Source: Thats how I got mine :P