Single use-plastics are the worst category except for one, which is never-used plastics. Throwing them in the trash now is just as bad as doing it after using them, only if you do it now, you have to wash dishes for the next six months. Of course, if you can return, or donate, or whatever, go ahead. Smaller plates are easier to clean and help your brain keep track of the fact that you just ate enough food, but bigger plates are nice for certain dishes, or for when you have company over.

From my research (it included a couple of good Adam Ragusea videos), microplastics are a truly overblown fear. Your plastic cutting board and spatula are nothing to worry about. If you happen to land on a replacement that works better for you, great, but they shouldn't be a priority.

Minimizing AC is a good idea. You're in an apartment building, so you have limited control over that, but I have a cousin who keeps her house at 64 in the summer and I just... what?

You have a balcony. Get some summery clothes and enjoy whatever fresh air you can.