My thought is to take a compiled list of property addresses saved in Excel and then run data scrape from Zillow and Redfin on each of those addresses, pulling the property details back into excel and into the appropriate table I have set up. 

I again suggest going back and reading my actual words and statement's, detailing how the books are cooked, I never detailed illegal activity, I detailed an executive branch changing how data is compiled and calculated because they didn't like the result, so instead of changing input's, they changed the calculation models until results fit the desired narratives. 

It is fun for me to compile my tax data to give to my CPA.

"What/who are some great resources that may can assist in the compilation of the first deal?"

I recently done some work for someone where i had to locate and compile lists of motivated seller leads( preforeclosure) in the 5 boroughs and just from the free court records alone could get 50 new motivated seller leads/oppertunities/prospects per day from it.With a thousnd oppertunities a month there is going to be some valuable deals in there. 

., you could hire an appraiser to assess the property and compile a report to obtain an accurate evaluation.

Quote from @Joseph Kirk: I would compile a list of contractors from referrals, and from Yelp etc.

They can introduce themselves face-to-face with the tenants, change the locks to control the property, get a copy of the lease from the tenant or sign a new one, etc.As for the old PM, it sounds like they owe you a copy of the lease and other paperwork (required by law), undelivered rent and security deposit, etc.I would compile your documentation and file a complaint with the Ohio real estate commission.

As @Ke Nan Wang said you have to hire an architect to make these decisions for you.On my projects I will compile like 5-10 inspiration photos based on projects I've done in the past, comps, and photos I find online, then I'll present those to the draftsman/architect.

As ground-up ADU builds gain popularity I hope we see some affordable options, like modular, but from what I'm seeing now the ROI just wouldn't be there.I'm trying to help spread the word about this law and compile as much information as possible so I can help investors capitalize on it.