Same reason you fall when its icy.
Check all of your weather stripping and all of the seals. There is probably just a spot where the stripping is pulled up or not completely sealed.
Wait until it warms up and melts
No.If they know who's car it is,they need to ask them to move it.if not,tough.
If you must my best advice is slow down to 10mph. Also try to get an hour on a skid pan (sloppy road supervised). It's compulsory in Sweden driving test. I have done it many times working for Honda...