Copper pipe help

[Crazyland]

I am a new AS owner and recently bought a 75 LY 25'. When I hooked a hose to the rear I noticed a balloon split in one of my copper pipes in the closet. It was the smallest of the two line. I cut the section out and went to Home Depot and they didn't have anything so I went to Camperland and the repair guy said that AS uses odd size pipe. Here are my questions;

1. Does AS use a rare size copper pipe or did this just expand? It almost matches up to 1/2 " flex tube but not workable.

2. Should I anticipate more punctures lines? If so, should I just try a temporary fix on this first one to see what else I am up against? I might have to replace the entire plumbing (sucks).

3. If I have to replace the plumbing, what does that entail or how much (est) would it cost to have done?

I am also getting ready to repair a leaking grey valve as well. Looking forward and thankful for your responses. Bob