@Linda166 I use a Nest thermostat. You have a few choices with it: you can set a range that the guest can adjust between, or you can just keep it locked entirely so the guest can't adjust it at all. I also like the fact that you can adjust it remotely from your smartphone, so if you're coming home on a cold night and you would like it warm, or you get a guest complaint about temperature, you can jump on and look at what's happening.
For the issue of guests coming upstairs, do you specifically address it when you take the guests on a tour? Is there a door that you can close (and possibly lock) between the spaces? Can you put up a reminder sign? They make some nice cast iron "Private" signs. I would also be a bit more specific in your description and rules that upstairs is strictly off limits: right now, it says certain areas are shared, but doesn't specify that they aren't allowed in certain areas.
I see that you have a coffee bar in your guests' space: could you add a bar fridge and tell them the kitchen is off limits? It blows my mind that guests just take your food and make their meals with it.
With consumable products, I don't put out any more than I'm prepared to lose. I would recommend putting out a nice glass jar with a few laundry pods in it, and putting the rest away. That's what I do, and it works.