MagicalCabbage13 LOL, it's always your main save that gets hit! After all, it's the one you play, right? 🙂
From what you've said and the pics posted, what you have happening is not what happened to me. I think you have something else (possible more than one thing) going on. Although, here is the bug report for what happened to me. There are other reports in other sections of the Forum as well. You may have read some of them since you mentioned the Residential Rentals connection which is believed to be one of the causes.
Neighboring Houses show as Default/Empty | EA Forums - 11903590
Your last pic showing the missing building in San Myshuno is an old bug from years ago. No way to get it back easily. So, new save. There is a way to do it if you really, really want to save the save, but it takes a lot of work. Given the state of your save at this point, I doubt it'll be worth the effort. But there are/were a number of posts about it here if you want to search. I never had to deal with the issue in my save.
For the other which sounds like a saving issue, I've seen several posts here re: saving issues. Here is the only link to an actual bug report that I found though there may be others depending on the search terms you use. Also, some discussions in other sections of the Forum.
saving and uploading to Gallery broken since introduction of Marketplace | EA Forums - 13307624
Edit: Just ran across this post which sounds quite similar to what you have happening. My files wont save and they back log to the very beginning | EA Forums - 13344727
Hope this helps.