When I removed the chrome roof rail trim it was screwed and glued to the roof rail. What is the product used above the chrome roof rail when reattaching? It almost looked like a thin adhesive foam when I took it off???

Must have been glued on at some point in its earlier life. Normally, the molding is a press fit onto the roof rail.

At least I think you're talking about the rain gutter molding and not the weatherstrip molding. W/S molding is screwed and insulated underneath the rain gutter.

I would think some double-sided tape would seal well along with the screws.

Yes, I am talking about the roof rail metal that screws to the roof. Just thought I would see if a light caulk or if there was a specific glue or something that goes on before you screw it on.

3M strip adhesive per this post:
http://www.camaros.net/forums/showthread.php?t=63674

I used weather strip that they use for pickup truck caps. One side has an adhesive on it the other has nothing. I put the adhesive side on the weather strip rail and then brushed some 3M weather stip adhesive on the other side and screwed it in place; worked great.