Can you put decoupage on a vinyl tablecloth?

An iron on low heat with a towel between the iron and the tablecloth.

I think you're probably talking about the plasticizer. A common one would be dioctyl phthalate, but there are others.

We did and it worked great

Yes

There are two parts to all vinyl liner pools, i.e. the walls, the bottom. The walls are nearly always the first 3 1/2' down from the top, and the bottom is the rest of the pool. In other words,...