My flip has a very similar issue to item 1 (caused by bad plumbing in this case) and the repair was quoted at half your price and included replacing a foundational beam as well.

However it takes a ton of effort to get these properties up and running-  we just finished the desert and it was a 6 month reno, and we are still waiting on items like a garage door.

a while ago we had received a free packet from comed with a few things to save on water. not sure what the items are called but it was something to put on the faucets and a water saving shower head

While these items don't necessarily add value to a home, they were needed to ensure a safe & sound property for future guests.

There may be some local state credits or things available that aren't tax specific- but local revitilization based items. 

I ran a quick search for "female house hacking" and it came up with quite a few items - I did not investigate them, but it did look like there are some you could try and get in touch with. 

I would like to discuss some items/issues with a property management individual that might have been in this type of situation before and see if there is anything we can do together!

Guess the next step is now that those smaller items have been addressed and its all been inspected..... wait for the next bill....... if the usage is still way high, then your unquestionably have an underground leak. 

There is value in "I live there comfortably with my family" so keep that in mind....All the above mentioned items are all valid, but the caveat is you actually have to FIND the deal that's going to be better than what you currently have. 

No point in estimating line item, you want to over budget and almost come with a ridiculous number for rehab so you know you can't lose