Laguna Bay 12 in. x 12 in. Cream Ceramic Floor and Wall Tile (14.53 sq. ft. / case)

Each case has 15 tiles that are 12 inches by 12 inches, covering 15 square feet. 800 square feet into 15 square feet yields about 53.3 boxes. In addition, the video suggests going 10% over to account for cut pieces, lippage, etc. so you may be looking at 55 or so.

how many tiles are in one case

We used bone colored grout and it blended in nicely.

Absolutely, I installed them over the cement floor for an additional bathroom.

No need to soak

I would think so. I have it on my floor with white grout and it is beautiful.

The surface is slightly rough- the tiles meet Coefficient of Friction standards for use in wet situations, but they're not recommended for shower floors because of their size. Because they're broken up by the grout lines, many small tiles are much more slip resistant than a few big ones. I've used them in apartment shower floors with no problems after 5 years.

Shower floors need to be slip-resistant and the bigger the tile, the slipperier. With smaller tile, the grout joints break up the surface and increase the friction. This tile has a fairly high coefficient of friction- I've used it on bathroom floors- and it wouldn't be terrible on a shower floor- but I'd recommend something smaller, ideally with an even higher wet coefficient of friction.

I think using them both on the floor and the counter tops may be a bit much, but not sure if I saw v-caps when I purchased it. What about one of those cultured marble pieces with the same color palette?

It's your tile, so you can use any color grout that pleases you. I've always used a beige or cream color that's close to the color of the tile. If you're using Laguna Bay, you're probably not trying to make a statement- you're probably just looking to cover a floor with something easy, unobtrusive and durable. I'm about to buy 3-4 cases to replace some discolored, damaged vinyl in the bathroom of a rental unit. FWIW, the darker the grout, the less scrubbing needed.