No lime (as in the brick mortar), just sand and portland cement. WOrking with it is like working wet beach sand. It does not flow and is porous (which is required to work right). It will be sandy on top, but it is great in compression which is what you want.
Following any one of the TCNA approved methods will give you a long-lasting shower. Personally, I still think Kerdi is the best one. There are distinct advantages of using a surface waterproofing layer - there is much less to get wet, the whole thing dries out faster. Tile and grout are not waterproof, and some moisture will get underneath (thus in a conventional pan, the sand and cement mix is good since it allow this moisture to migrate to the weep holes). With a Kerdi shower, you only need one mortar bed, then apply the membrane rather than building two making for a lower shower floor height, getting your liner to sit flat without bowing out the corners or bottom edges of the cbu, and another layer. In a conventional shower, the cbu and setting layer of the pan can get and stay damp for a long time if the shower is used a lot; doesn't happen with a surface membrane. Plus, with Kerdi, you drywall the walls and the curb...much easier and quicker. No need to tape and mud the corners or joints, either as the membrane performs that task. You will need a rich mud for over the kerb, as it needs more stikum and strength to hold together on the lath in that thinner layer. A Kerdi curb can be smaller because it doesn't need as much mortar over it or the lath.
Check out www.johnbridge.com for tiling help whichever approved method you choose.