That's all a matter of preference. Not seeing the tile, I generally prefer diagonal. For some reason I prefer not to have all the lines in the same direction, so having the tile at an angle to the wall and cabinets just looks better to me. But some people don't like that at all. There's some good discussion on this in Bathrooms if you want to do a search and read while waiting. No feelings about grout lines other than I know I can't keep them clean, so I would go small. Not sure if these are regular tiles or vinyl, but for regular tiles make sure you ask about lippage. That's when the tiles are not even heights, less/no lippage is better, but harder to do. I don't know all the technical stuff, but good info on Bathrooms about this too. Maybe just bringing it up will encourage them to be on their toes?

the heights are different in the 2 pics. The second is higher-note inner shelves on the sides. The first has a wider cooktop-more burners-no inner shelves-ovens outside the area somewhere. The cook in the first picture would be moving side to side a bit more while cooking but reaching outside the space for supplies. The 2nd person would be fixed in that stance with needed items on those shelves-less side to side movement , but more head and shoulder room, so it works. What do you need for what you will be doing, how it's set-up and your body type? They are both nice:the first is more formal,refined. The second is more useful/inviting.If you are going higher-use the space wisely as in pic 2.

I would think light colored subways, especially glossy ones, would be quite easy to clean, being so smooth and flat, and with the glaze to protect the tile. I am an easy-clean fan, too, and made probably one of the 'worst' choices in terms of cleaning...Rough-faced slate (or quartzite). Anyway, it's rugged and light colored, and likely somewhat porous...and has large grout lines. But I sealed it and it's not that much trouble to wipe down. It helps that we bumped out our rangetop a few inches, but we're not careful about it, and it's a big, Wolf gas rangetop, so if a backsplash is going to take a beating, it should be in this situation. It's been up about 20 months and isn't discolored or stained. I think you'll be fine! If something is seen in magazines/inspiration kitchens that is really a poor functional idea, people on this forum will talk about it, but not do it for themselves. The fact that so many have tile backsplashes here says to me that it's a workable idea. If it were me, I'd stick to a grout color that will take some spotting without showing it off (gray or tan instead of white)...Just in case. :-)

Asbestos containing tile can be found in both the 12"x 12" and 9" x 9" formats. Also asphalt tile contained the mineral fiber in greater amounts than vinyl asbestos, and it was mostly produced in the 9" x 9" format. The black adhesive may or may not contain the fiber. How you remove the adhesive is your business. Since the fibers are embedded in the adhesive matrix, it is highly unlikely that you will make any of it achieve an airborne state regardless of how you decide to remove it. You can have the adhesive residue tested for the presence of the mineral. Perhaps it would be best to contact a company that can scarify the concrete for you in preparation for the acid staining you want.