No. There's no prohibition on open carrying a shotgun, a rifle, a short-barrel shotgun (SBS) or a short-barrel rifle (SBR), whether loaded or empty. The last two items, however, are NFA items and you'd best have the federal tax stamp to go with them. If carried in a vehicle, the rifle or shotgun must be unloaded (but the SBS and SBR can be carried loaded if one has an LTCF). If that has you confused a little, full-size rifles or shotguns are not listed as "firearms" under licensing definitions, but SBSs and SBRs qualify due to their shorter length and fall under LTCF protection.
Yes, she's wrong. There is no such thing in the statutes as either open carry in a car or concealed carry in a car, there is only carrying in a car.
18 Pa. C.S. § 6109. Licenses.
(a) Purpose of license.--A license to carry a firearm shall be for the purpose of carrying a firearm concealed on or about one's person or in a vehicle throughout this Commonwealth.
As you can see, the purpose of the license lists two separate reasons - carrying concealed on or about one's person, or carrying in a vehicle. It does not specify how the firearm is to be carried in (or on) a vehicle, be it on one's hip, on one's lap, in a glove box, hanging from the ceiling or stapled or taped to one's forehead. Court rulings essentially state a vehicle is a conveyance to get one from Point A to Point B, so such could include a car, a truck, a train, a plane, a taxicab, a bicycle, a tricycle, a unicycle, a motorcycle, a moped, a skateboard, roller skates or blades, a horse or a riding mower. 75 Pa. C.S. § 7727, however, does not allow the carrying of firearms on ATVs or snowmobiles unless hunting.