Our granite came sealed with a "life time" sealer. Had we had a seam, maybe they would have had to apply some sealer there on site, not sure. Our travertine backsplash I know about because we installed it our ourselves. We stuck it up with the thinset one day, grouted the next, applied the 1st coat of sealer the third day, and applied the 2nd coat the day after. It's possible that the thinset and the grout didn't need to be 24 hours apart, but the thinset does need to dry first. The drying time before sealing was 24 hours for sure, but the sealing process is quick. The second coat is even faster. After everything was dry, we caulked along all the margins where one material met another (counter to backsplash, backsplash to cabinet underside) and the corners. It seems to me that the tile place recommended resealing every couple of years depending on how much splashing, and therefore washing, you actually do. The only place I routinely splash is behind the sink.

If the counter installers are willing to mount to the granite let them. If anything goes wrong it is on them. Most of the time the DW goes in well after the counters, and no appliance installer is going to mess with trying to attach to the granite. I have seen small filler strips that match the cabinets epoxied to the underside of the cabinet, but that was for a higher than regular counter height.

You'll be fine, as long as the head of the screw is bigger than the drilled hole. Even then, you could add a small washer on the inside to make up for the oversized hole.

There are pros & cons for each type of reveal: Positive--where the sink shows/granite is cut slightly larger than sink Pros: easier to clean b/c you can see the gunk and can easily wipe it off (it only gets nasty if you leave it there) Cons: silicone (caulk?) is visible, but if they use clear you won't see it when it dries Negative--where the granite overhangs the sink Pros: You cannot see the gunk buildup or silicone Cons: -- You cannot see the gunk to clean it. -- Dirty water/food can splash up & under where you cannot see to clean it. It's difficult to see underneath w/o leaning way over & into the sink. -- Dishes have been known to break b/c when you lift them out near the edge of the sink they dish hits the stone counter & can break (or, if the dish wins, the counter could chip...but I'm not sure how likely that is). Flush--where the granite & sink are the same Pros: -- easier to clean b/c you can see the gunk -- no platform over or under for the gunk to collect Cons: -- more difficult to do perfectly -- silicone is visible, but if they use clear you won't see it when it dries You will find proponents of all three types of reveals here...but in the end it's what works best for you. Good luck tomorrow!