It's a sad way to become the owner of a beautiful trailer like your '68 GT, but I will venture to say that with time, it will become a joy to you, and a warm reminder of good times with your parents.
Welcome to Airforums.com,by the way, you will find it a very good source of info for your trailer.
As for the hot water heater, look for a loop that isolates your water tank from the cold-water supply. This is often done in trailers to make it unnecessary to add 6 or 10 gallons of anti-freeze to the water heater for winterization.
Water taps in AS (Airstream) TTs (travel trailers) usually use the pattern that the handle of a closed water valve is at right angles to the pipe it is in, and the handle will therefore be in-line with the pipe when it is open.
See if that helps.