Drop in tub for the standard installation

I want to use drop-in tub (without the lip) for standard installation. I wonder if anybody knows a reliable procedure, other then caulking the gap to death, to prevent leakage. Tub is plastic jacuzzi, wall is cement durock board, will have 6" tiles. I'm thinking about "Great stuff" or somethig like that...
I also have a question about how far from the wall to extend a coupler for Delta spout, the fancy long plastic one. It is looks like no indication in the manual, and parts looks far from obvious....

tub

If you mean it is going into a recess and the tile is coming right down onto it, then there is no way to do it, unless you also purchase the "tile flange kit" that adapts it for recess installation. The spout adapter can be installed anywhere within an inch or so of the wall.

Thank you!

I did look up the flange kit on jacuzzi web site, and it is looks like what I need.