All in all - owning a place to rent to other people is a business, and business decisions need to be made based on that cold hard facts and not on an emotional basis, unless someone wants to quickly go out of business.

Here’s some feedback based on your situation:House hacking is a fantastic way to reduce housing costs while building equity.

Look for properties with low taxes, separate utilities, strong demand, and potential for rent increases.

Since you have no contract, there is nothing that says you do not have to pay if you are not satisfied, and your spreadsheet would seem to indicate you owe him the money.Similarly, since you paid him for previous work on the spreadsheet, and the spreadsheet shows you owe him for additional work, your argument is not very strong.

Where are you based out of? 

There is still strong demand for Austin housing with pending sales in the metro up 16% compared to last year (and up nearly 30% in Austin).

3 recent national studies show that the rent to value ratio is at an all time worse (what they really studied was cheaper to rent than buy, but there is strong correlation).  

Not at all.... the rent is based on the market rate, so if the units are all different...size/location/lay out/age etc etc... they would have different markets rates.

You just discriminated against them based on family status.It's good to have a heart-to-heart talk with them about what they can afford and see what they want to do.

My mentors (both successful investors) swear by building strong relationships often saying  "It's all about who you know,".