You want to do this right, and none of your thoughts would pass code. I think you need to crack some concrete to put in a proper trap and shower drain. It also needs a vent, if it doesn't already have one. Also, even though the shower is on the basement slab, you need a pre-slope and liner, then a setting bed for the tile. Do not build this without a liner. There are surface membrane techniques that can also be used that would pass code. Check out www.schluter.com for their Kerdi system. There are others that work well, too. Check out www.johnbridge.com for tiling help. The plumbers here can help with the plumbing issues.