Built in 1982 and renovated in 2020, the property has recently undergone extensive capital improvements.

Property Type: Do you prefer residential, commercial, or mixed-use properties?

Depending on the size of the ADU vs the main property, you would probably be looking at either a "heavy rehab" loan - or a "ground up construction" loan.

Now, I have been successfully investing in the San Antonio market since 2019 with 6 rental properties in my portfolio.

TP spends 100% of their time in the asset management of these properties (not property management).TP has recently invested personally in these deals and owns at least 5% of Property A.

I have decided to partner up with another investor to buy this property together.

It seems you are the only person who understood the question wanting to know what a seller makes (not even sure how or why you think that).As a typical part of the DD process it is not uncommon to ask for property/entity tax returns.

That 150k will only get you two houses.The question there becomes will the property cash flow with a loan of 225k.

As a San Jose licensed property manager and investor, a 5% flat fee can be reasonable depending on the property. 

All of my properties are A/B locations with responsible tenants who make their payments through an online payment system.