question 1: Either setup should be fine in snowy/rainy conditions, they aren't long tube CAIs that can get water in them.
question 2: the noise people are talking about is engine noise. You will hear your engine more with a CAI, it is less restrictive and doesn't insulate noise like the stock intake.
question 3: expect 2 - 5 hp gain and some decent low end torque gains (maybe up to 8 ft-lbs)...but a CAI by itself is not going to make a huge performance difference.
If anyone doesn't agree with my responses, feel free to disagree!