However a out of state investor bought the debt from the bank, the investor recorded the lien with the county (Fulton, Atlanta,Ga) but not the amount of the lien.

It may be too late - but you can go to the county tax records and look up by address to find out who owns the property, then go to the county's "official public records" and search the name and see if there are any other liens on the property.  

I pulled their purchase amounts from the county records, the current interest rates at the time of their purchase and calculated a ball park figure of what their mortgage payment could be.

This is brand-new relationship, and having dealing with lease option deals for over 30 years, it's a common occurrence when dealing with listed houses.Let's say you have a hundred thousand dollars house and is listing agreement with the commission at stake of 3% or $3000.You may want to go down to the broker of record and asked him to release you of the listing for say thousand dollars.

I want to know how to look up property and state records and I'm not having any luck in Maryland its different can you please give me some insight

Who has a track record of doing these types of deals! 

Just for the record, I can handle property management, but I am thinking I would rather buy low enough to afford to pay for it with my cash flow.

Ask questions, check county records and historical society.

I am aware these numbers are ProForma and I will be doing my due diligence to get proper records but I believe the numbers show promise and deserve to be looked into at the very least.

Yes, if you buy the first mortgage you are in good.You need to look at all the recorded documents for the property to figure out what is going on.