I was going to suggest airline tubing, however they are not very thick and you would need to purchase one with a wide diameter to allow the plug to maneuver through. With PVC, you are also looking at a fairly thick tube in your tank.
Yes it is. Get it clean with some acetone (nail polish remover) and then wash it off thoroughly ad wait 24 hours before putting it in the tank. Acetone is a strong solvent of CPVC and PVC and you want it to cure before putting it in a tank.
They mostly use it for hot water applications. It has the same outer diameter as copper.