I wrote this b4 doc so I'm not going to alter it. LOL
PVC or rubber, you can buy just the return line on fleebay. Asian fitting sizes are different then American. I use a coolmate3 and I believe the fittings are 5/8 or 11/16. Asian ones are smaller and metric.
I use the same torch that you referred to. The power cable is the water supply line(nut), separate lines for water return and gas (barb fittings), 3 hoses altogether.
I think you got the wrong hose if it's for gas and power. The cable will not last with water running though it. I suggest you buy new hoses and torch it isn't that much and you know what you got. Just make sure your ground cable matches it your torch or buy 20ft and be done.
On the water cooler thing, look for a used, maybe even a broken one to repair. Everyone that I see built that is worth a dam got a couple hundred bucks into them.