The 2-rail trucks ARE double insulated, so there is not chance of a short using metal couplers.
Standard 805s work or the new ones with standard shanks. Not sure the number on these.
The underframe sits up inside the body about 1/8 inch. Mine came supplied with a shim plate for the coupler mount that got down level with the body. You could probably make you own easily enough out of a piece of styrene or wood the right thickness. It also looks like the same one that Atlas O included with some of their boxcars - the USRA OSB for one I think. Pecos River is pretty much out of business, so it might be hard to get parts from him. However, if he has any and you can contact him, I'm sure he would send some.