To buy a long gun you WILL need an FFL in PA since you're an out of state resident. You'll also need to make sure it meets the NUMEROUS restriction requirements of NJ. If you look up banned in the dictionary they show a picture of a gun with the state of NJ in the background with a big red circle crossed out. You also need to have a NJ FID card.
You MUST have any handguns SHIPPED to a NJ FFL where you will need to have a nics check run. You MUST have a NJ handgun purchase permit, you may NOT buy more than one every 30 days.
If you don't a FID or Pistol permit right now, don't bother buying any guns. There's a 3 month + wait right now in almost every town in NJ.