Get some alien tape, wipe the surface with alcohol, wipe the feet of the microwave with alcohol and apply the tape to the microwave. When positioned the way you want, remove the other side of the tape and voila! it stays where you put it. For it to fail, all four pieces of Alien tape would have to fail. If that continues to happen a pool noodle works great so long as it's not covering a vent. I usually cut it up into a couple of pieces and place it behind the microwave to keep it from moving. Not nearly as satisfying as Alien tape, but at least it works.

I warm my plates sometimes with a damp square of kitchen paper in between. The water in the paper heats up and does the trick. I always do scrambled eggs but I use half power and stir after 45 seconds then after 20 secs and so on until done. I par boil vegetables for roasting and soups to save time. We keep our bread in the freezer and defrost before use, also rolls, banana bread, un-iced cake etc. I've heated up a wet face cloth to wipe my grandkids' faces rather than wait for the hot water to come through. More energy efficient. If my coffee or tea goes cool when I'm on the phone I'll reheat it for 20 secs.

the vent behind a built in stacked mw oven only vents above the wall cabinets to the kitchen so there should'nt be any reason why the exact same construction couldn't be used at counter height with a suitable sized opening (width of mw and 45mm deep?) along the splashback to allow air to ventilate but safety could be compromised if the hole was accidentally covered so a raised edge or "chimney" around the slot could help stop items being placed over the opening or crumbs etc falling into the hole BUT if you had a non built in mw the ventilation requirements are less strict as there's more air space around the appliance..seems to me that like the manufacturer who provides the best customer service to clarify this issue might be the one who gains your business...good luck, but i wish you had the option of a wall mounted appliance that is so much easier to use

.I would always put fridge where it is accessible without getting into the main cooking zone and group oven and stove . Extend island to balance cooking zone, and reduce wasted space I would still delete the door to utility it really is wasting space and entering it via the hallway isn’t that big a deal anyway, for the compromise you are making and lost storage in the kitchen.