I' m new to REI and I'm looking at house hacking as my point of entry in the Baltimore MD area.

In terms of cash flowing, I would say its gotten harder as the Philadelphia real estate (entry level homes) have appreciated.

You should have gotten some info about the system along with the home, including the documentation about the system like the permit, paid invoice, warranty info, equipment manuals and data sheets, net metering agreement, production payment contract, name and contact info for installer etc.

I can't sign a new cell phone plan and then demand unlimited data after the fact. 

I think it's a great deal for all the data it provides.

I like how you use data from previously sold properties to calculate the property's value and sell price to identify the margin available to help cover repairs.

Then have them cross reverence the data with local tax records to find the owner info.

I was going through the AirDna data and it seems promising but I believe their numbers may be over inflated.

Yes, the unit is a legal 4 family and each floor has its own bathroom and entry and exits. 

The entry cost to becoming a certified inspector is not expensive at all.