Can it still qualify for 100% cost segregation?

As a pure investment it looks okay, but with a primary residence for my family thrown in at zero additional cost, it looks really really great.  

Explain the potential damage and costs involved with the water running continuously and put it in writing letting him know that he is not to touch the chain again, that if he needs service that he should notify you and you will take care of it.Additionally, there are devices you can get that will alert you if your toilet is running.

For the cost of filing fees and service fees you get someone with the wherewithal, authority and motivation to fix your problem.

Every item has a lifespan and collecting maintenance/replacement costs should start as soon as an item is put into service.There are lenders that will provide HELOC on rental properties but they are not extremely easy to find.  

However, that requires us to dig down the basement floor to meet the ceiling height requirement (it's got the egresses and 2 exits already), and I think that can easily cost us $100-120k.

A bad tenant will cost you much more than that.

So the partnership would be to split the down payment and other fees, redcue capital expenditure risk in the future, and we would like to do some work on the basement & backyard which is also going to cost capital.

To answer your question, it is possible, and quite costly, to have individual meters installed by the city.

If your all in costs are 115k, the loan amount would be 92k (80% LTC).