"4- Should I rubber mount pipes for vibration?"
There are a lot of ways sidepipes are attached to replicas. A friend of mine had one of his rear hanger brackets break from metal fatigue. Even though it was a thick metal bar, it eventually fatigued. For that reason, I think an "L" shaped rear hanger bracket is stronger and rubber mounting is best. Below are a couple photos of how ERA mounts sidepipes. The first is their hanger bracket, which is securely welded to the pipe. The hole at the other end is bolted to two thick, reinforced rubber hangers that are bolted to the chassis (2nd photo below). You can't see it in the photo below, but the tops of the rubber hangers are angle cut to fit flush against the floor of the car to prevent them from rotating.
