I can answer a couple of those:
1) .100 is 1/10th of an inch. That's a pretty healthy thickness for aluminum.
2) It will certainly be weaker in this area. It will entirely depend upon the amount of stress that it sees. If it's near a corner or brace or the bow eye, it will likely split. If not, it may be ok. Is it below the waterline? if yes, then it would probably be better to have it repaired and not worry. If it is above the waterline, you can probably get by with some regular checks of it to see if it changes or begins to open up.
3) If its a relatively small gouge, 1/4" or so, it should be a relatively easy weld repair. This would be the surest way to eliminate any potential future damage. You could also look into JB weld, but that would probably stick out like a sore thumb and could still have issues in the future.
Being that it's a brand new boat, I would probably get it welded and repainted if necessary and not worry about it again. But if you're looking to stay on the water for minimal money, JB Weld would do for a few years.
Good luck and Happy Holidays!