1) The sunglasses protecting your eyes depends on your eye health. You are damaging your eyes slightly no matter what. What matters is if your eye health is good enough to allowing them to heal. An analogy is like any time outside is causing some skin damage even if you have layers of sunscreen on.
Plenty of people go sunglasses only, some even go no eyeprotection. it's up to you, and depends if you're doing this often. If your eyes are hurting or feel tired that evening or day afterwards; or going inside to the lodge you are snowblind and can't see for a few minutes, those are signs your eyes are getting too much light.
2) Glasses under goggles are not uncommon. But, you need to look for goggle models that are specifically made for this will be labelled OTG (over the glass) goggles which will be bigger.
I don't understand the reasoning for clear goggles and tinted glasses. Why not use tinted goggles and using your clear glasses? (which is what most people do). The tint will go over your entire field of view so you see "more" peripherally, rather then having the slivers of brightness still come in
Be sure to pick up an anti-fog wipe-no matter how good your glasses are. The smith no-fog should only be $2-$3 and reusable .
If you breath on your glasses and they "fog" then you need this.
This is for your glasses not the (inside of) goggles.
Do not use wipe or clean the inside of your goggles unless the factory coating is already ruined and you're just trying to make do.
Edited by raytseng - 10/13/14 at 10:42pm