welcome tremontana.. question 2 first, have you noticed any other water anywhere else in the car? the seats themselves, the trunk? etc? i have to state to obvious first and that is to check the window and see if the seals around them are good. also check the seems on the doors are they missing or cracked so bad that you could foresee water getting in?
now question 1, i think the dealership is right, last i remember if that is broken, some gears get outta wack. but i vaugely remember it being a problem in neutral not park. if the dealership says this is what it is than get it fixed. you dont want your Girlfriend to forget about it one day and find the car down the road in someones garage.