Good point. SmileWavy

Omnigrip will stick tile to drywall. No mixing and it doesn't sag. HD has it among other places. Get a grout with matching caulk. Grout the tile and caulk it to the counter. It isn't a shower.

We have a pot filler behind the stove. Pretty handy. Though i kind of wish it were hot water (or both?) so my pasta water would boil faster.

It doesn't if the painted walls are glossy or not uber clean. If the wall is to be covered with tile then the backing, drywall, cement board or plaster will never be seen again because you don't remove tile and save a wall.

So run a belt sander over the painted surface with a 24 grit belt and seal the roughed up surface. Modified thinset or mastic will stick to that.

Preparation is key but that's the easy part. Getting tiles on a wall that look really good from an acute side angle is were the experienced tower over the novice.

Yep, especially if you have under cabinets lights. Once those lights are on, it will show every signel imperfections,all shadow will show up if the tiles aren't flat. Ask me how I know especially some of the Carrera Marble isn't always the same thickness. Now I take a flash light and shine at the tile from the side or lay the flash light flat to see if there are any imperfections.

I would check the area with a straight edge/four foot level to see how flat it is. Drywall can be significantly wavy. If it isn't flat I would rip out the drywall and start over with hardiboard. The drywall isn't an ideal backing and it doesn't make much sense to spend time bailing out a non-ideal surface. My experience with tiling has mostly been trying to take shortcuts and regretting it later.