Also, because of the extreme sizing that usually comes with slate, I would strongly recommend that you don't use spacers. Instead, lay a few of the tiles out dry with the 3/16" grout joints, and then find out what your coursing is (a course is the dimension of one tile plus one grout joint). Figure out where you want to start your layout from, snap two square lines from that point (if you need help with this, let me know, and I'll explain it), and then grid the room out in 2 tile by 2 tile boxes. That way, no matter HOW much the size varies, the tiles will remain straight.

When we mixed the grout (unsanded)for our backsplash, it was very stiff, making it a pain (more work) to press into the 1/16" joints with the float. We really had to work to get it applied. I don't know if it's possible, but maybe they mixed in a little more water to make it easier to apply on the sample boards. When we made our sample boards, we mixed up small amounts of the grout by hand to use, as we were just wanted to check the color. We mixed the grout used on the actual installation with the drill and an attachment for mixing concrete type materials. You might show them the sample boards and ask why it's crumbly.

A lot of time, basic 6x6's will come with tile lugs that create a predetermined spacing for the tile. You need to find out if the tile you are interested in has that. If not, then remember that the thinner the grout lines, the less wavy your wall has to be or else you will have problems. If you are doing this from the studs out as new construction, then be sure that you use a long enough level to check to be sure that all of the studs are plumb and they are all perfectly in line. If one is off, it will throw off your whole tile spacing if you are planning on thin grout lines. Thicker grout lines are always more forgiving for a novice tiler.

Ok so, so sorry but here: Master- 1) Lay-out is awful. You shouldn't have that small tile at the inside (a pro balances the lay-out prior to install). Yes your concerns regarding uneven and improper slope are valid. Pretty basic standard for tile installation, especially on a shower floor where proper pitch to drain is imperative. Being concerned about the damage occurring from tearing it out is a mute point as you will have major issues as it is. 2) As others have stated, that should be caulk and always caulk at change of planes, not grout. And no, it isn't common for professionals to install on a surface that isn't plumb and flat. If either the general or the tile contractor do not shim and level to prepare for tile, then standards are being ignored and you have a problem. It's poorly done. 3) That is the very cheapest drain assembly available (if it was speced and this was a very low end build, then maybe that was to be expected but as a customer you should be aware of the quality of the product being used). Very unprofessional job around the drain. It should be cut so nicely around the drain that you don't even notice the grout. It is definitely not an "average job". In the tile world, we would call it a "hack job". Guest - 1) Multiple possibilities for the grout pinholes, all related to skill and craftsmanship. Could you dab grout in those places and hope it looks a little better? If you bought a new car would you ask them to fix the paint or dents before you drove it off the lot? You shouldn't need to do patch work on something new. 2) Caulk but remove grout first. 3) Caulk and color match, not clear. Clear is a bad idea there. Now, I'm sorry if we sound harsh. It's an exciting time to move into a new home. If consumers do not hold the builders to basic standards, there will continue to be builders that take short cuts and perform sub-standard work. ALL builds should adhere to basic standards and there is no excuse for what you are seeing. (I hate to say it but I'd be concerned about the methods used to build and waterproof the wet areas, what you can't see, based on what you can see). One place to start is to ask your contractor to document how all aspects of the tile work conform to TCNA industry standards.