The benefit of old homes imo is that I go in and redo all of the systems and have basically a brand new house that I know was done right bc I oversaw everything.Most new homes are built with cheaper materials than the homes built in 1900.

I will suggest that a seminar that sells training materials only would not have helped me. 

Educate the land owner on the potential profit run the numbers and go over the basic proxy and blue prints.Make sure you have a seasoned and qualified Builder/GC because they can be a deal killer with wasted time and inflated material and extended completion dates.

Overseeing tradesmen while they work on your properties sounds like material participation to me.

It does not cost the landlord except for the labor and materials.

I don't think anything anyone offers is "evidence" in court because you would be backing up your claims with documentation such as the lease, or quotes for work or material prices.

Some of the costs quoted shock even seasoned flippers as they are lower than even material are in many markets. 

I am sure there are other good choices out there, but strongly recommend them.Stessa is lacking tenant communications and maintenance tracking, but overall stands up pretty well as free, or nearly free.Buildium is pricey and has a learning curve, but if you are going to exceed 20 units, definitely look to migrating to a real professional package like buildium

Do you have any more materials to share with me about the market? 

HVAC unit is package unit on right side of the unit.