use your old sim and your number and plan stay the same. when the new phone comes in charge it and then insert your old sim in it. read the booklet it'll tell you how to insert the sim card
have you had the transmission fluid level checked? the cv joints might be gone on the front or the brake pads. either way its gonna cost $$$$$$$$$$$$ to have it looked at and fixed properly if you dont know how to fix it.
if you are not detected by the rest area security or the police that patrol them. and if there are curtains hung on the windows to make the truck private, i don't think they can give you a ticket for indecent exposure/public nudity.