1.What type of tiles are best along the pan? What is the difference between cove tiles and sanitary cove tiles? In most residential applications, the flat tile will be run straight down to the pan. One way or the other, the sanitary base would be the one you have to use, if you were to go that route. The difference is simple. With cove, the flat edge where the cove ends (the edge that would be facing the same direction as the face of the tile) is unfinished, made for the floor tile to abutt it and continue on, for a smooth transition from wall to floor. Sanitary base is made to sit on TOP of the floor, with that edge being glazed the same as the face of the tile. 2.The existing Walls will be replaced. What is the VERY BEST waterproof wall material to put behind the shower tiles? Is there something improved over greenboard? Can the upper part of the wall just be finished and textured like regular drywall? First off, greenboard can NOT be used as a tile backer in a shower. It MUST be cement board, unless there's a waterproofing applied over the top of it, and personally speaking, I don't even agree with that. Now, cement board is not waterproof, and there has to be a vapor barrier placed behind it, unless again, you use a waterproofing over the top of it, and for that, I would go with either one of the several available roll ons such as Laticrete's 9235 or trowel ons, such as Hydroment's Ultraset, or a sheet membrane like Kerdi. As for above the tile, you can stop the cement board just under where you want the last course of tile to be, and continue to the top with greenboard, which can then be finished however you like. As for tiling around the front side edge, could you elaborate a little bit on that?

The above is the Salient cast iron. The OP was asking about the Purist which looks like it was designed to drop down into the floor since it doesn't have a apron. Which for a shower base designed for people who don't want grout, doesn't make sense since they would need to fill in that space with, tile.

HI Mary, have you considered saving money using white tiles topped with a show-stopper, multi-color border or "chest-rail"? This way you get your color on the walls that you can even replace down the line if wish without redoing the whole wall. For the floor, we picked the brown from the wall and did small 1" mosaic-style so would add grout traction (very important on shower floors: do with a rougher finish tile if can) I don't know where you are but check out this approach we did here in the Southwest. Granted, it's Spanishy, but you could do something more quiet that matches your overall home style.

I would get myself over to Yelp, and research local flooring stores that sell product AND do installation. Read through all the reviews. Get a comfort level that you can work with the folks in the store, and that they stand behind their products and work. Even more important when you're doing the whole house--it's a big project! When things go wrong, and you can read through many, many threads about that, the manufacturer points at the installation, and the installer points at the manufacturer. It is an uphill battle, it can get $$$legal$$$, and when I put flooring in our whole downstairs, I was (rarely for me) less concerned about saving $1/sf than I was concerned about not having anything go wrong, and in the event something did go wrong, having a long-standing store with LEVERAGE over the manufacturer to reduce my risk. I'm glad I went the way I did, and after all my questions, I went with the decades-old family-run store with the great reputation across town. They made great recommendations, and made sure to offer me all my options/upgrades up front, and didn't try to talk me out of anything that was important to me: (e.g. I asked for no quarter round to have a sleeker look of baseboard meeting flooring). Be sure to ask about additional costs for moving furniture, and which crew they will send. In my case, they sent their "best" crew (most experienced), and I agreed to wait for them. They picture-framed our hearth (mitered corners-looks great), and "beefed-up" a stair step that leads to our front door, making it wider/safer--at no extra charge. There are things that a homeowner might not know about (cheap glue?), moisture issues if you're on a slab, etc. These are just my thoughts and experience. You can also read through a lot of threads in this flooring forum to see what goes wrong for folks, and get a better idea of what questions to ask. Good luck!