Beware of any grout that does not require mixing...
You might want to go over to
www.johnbridge.com. It is VERY important to make the pan properly, and you'd be surprised at how many people don't do it! You'll get people rant that they've done it that way for decades, and it works. It might not leak, but that doesn't mean it will perform properly...
The industry standard REQUIRES that the waterproof membrane or surface MUST be sloped. The tile on the top is NOT waterproof, so it doesn't count, although it also must be sloped as well.
There are a fair number of epoxy grouts out there, but they all require mixing of the components. Anything else, is basically a fancy caulk - stay away from them for grout. Epoxy grouts are often used in hospitals, food prep areas, and are making inroads into domestic applications. They are significantly more expensive than cement based grouts. Unless you use something like Dilex from
www.schluter.com, you need to caulk the changes of plane in the shower...unless you make a mudded shower and walls, your transitions will almost certainly crack and should be caulked.
There are several acceptable ways to construct a shower...you should read up on those a little to ask you contractor some key questions to make sure yours will be done to current national standards to ensure a long-term satisfaction.
Go over to
www.johnbridge.com and read up some in the Liberry (sic). You'll find articles there on the proper construction of a shower, and they can answer pretty much any tile questions you may have.