It's called 'Teflon' tape but isn't Teflon, is it???.
Some research has revealed that it is indeed. Teflon is the trade name.

It's PTFE tape, or plumbers tape and is Poly-tetra-fluoro-ethylene, from memory.

I knew a shooter in Brisbane, who said he used to wrap his cast .458 bullets with it and shoot them with full power loads, successfully. I didn't see the results on the targets though, so can't comment on the accuracy. I have tried it in my old .303 and wasn't impressed with the accuracy. I get much better results with Paper Patches.

As for the liquid to wet the patch, I reckon that a little PVA wood glue added to the water would be ok. I just use plain tank water and have no problems with patches slipping.