Based on what I saw in Dawnguard their lost magic looks like alteration to me, the underground Falmer seem to be really talented alchemists and good with bows and one hand swords.
I would guess a Snow Elf would be: +10 Alteration, +5 Restoration, +5 Archery, +5 One-Handed, +5 Alchemy, +5 Speech.
And their racial power would be basically like a Fus Roh Dah spell but affecting a huge radius all around the caster. Racial ability is 50% shock resistance.
I would probably play a Snow Elf like a mystical-archer. A bow with a paralyze enchantment, Elven or hide armor, with Alteration and Restoration, a dagger for backup.
