@Christyn0- They are telling you what they need and want to make their stay more comfortable. It seems reasonable to me - the extra pots and bowls as well as telling you about the things they did to make it safer for them and the baby. Reading your profile that you are a chef, I would expect that the kitchen would have absolutely everything that a chef would require in a kitchen including several large bowls, several pots and pans, cutting boards and full cache of utensils and plates.
After reviewing your listing, it took me a long time to find the stairs they were talking about and there is no picture of the water cooler. Perhaps mentioning the stairs in the listing - say that the bedrooms are on the second floor or have them agree in your house rules that stairs are in the apartment - there's a new feature for that. And perhaps providing a picture with the water dispenser will help. People don't read the entire listing and the first full half of your profile is about a discount and instant booking. I almost didn't read anymore myself. Perhaps this is not the most important thing to list first? It's just a thought to make sure folks read the important details.
With the sharp corners, stairs, and definitely adult feel of the apartment, perhaps you might say in your house rules that it is not suitable for children under 2. Parents can choose for themselves of course, but you would be setting an expectation.
Not sure what to tell you about the A/C and his blocking mechanism - perhaps the fan blades can be adjusted away from the bed? In your listing it says that it's new so maybe this is possible? It's a little nit-picky on his part, but it's probably keeping him awake so he's tired.
You can always add new curtains, but if no one else has said anything in 2 years, that's just about the guests and what they need for "privacy". Just take it for what it is - they would prefer more - frankly, I can't even tell from your pictures what windows they think people are peeping in on them through. Looks to me like they are the type of blind that allows light but blurs everything inside and provides plenty of privacy. You might simply respond with: Thank you for the feedback on the blinds, we will look into making a change. That way the guest feels like his words are heard, even if you never do anything about it.
Hopefully a big deep breath will help. They had expectations, the expectations are not being met, it happens to all of us from time to time. All you can do is solve the things you can solve and hope it's enough.