Of course, with all things, the situation varies and no one on these forums has seen your underlying documents and the actual terms, and thus, you should consult with legal counsel specific to your situation. 

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

When you are within two years of purchasing make sure to have good tax returns to submit as lenders will want tax returns for last two years.Use the money you have saved and your tax returns to buy a duplex/triplex with an FHA loan and house hack.That would be my game plan in a nutshell.

This is also programmed into our PM software, so it happens automatically.Our lease also states what rent will be applied and in what order and also a security deposit.So, you may want to check these documents to see if this is covered with your PMC.While we always try to be fair with our clients, we also have to generate enough income to pay our bills. 

I know how to work my county's website and I was wondering what "document type" I should be looking for as far as probates?

Now we have to submit the plans and apply for a permit and have an inspector come out to review the conversion from 30+ years ago

All of which are well documented on the forums.

The issues is time reviewing everything, we'll need all your documents and if we see a number wrong we can't go into the tax software to see what went wrong, it would be a lot of back and forth.

Lender 2 requires 6 months reserves. they want the borrower to document any large deposits and they want mortgage statements on any investment properties listed on the 1003.The point is different lenders do different things and it's important to not generalize as a broker, but interview the borrower, find their pain points and marry them with a lender that will minimize those pain points for a successful close. 

Thanks @Chris Seveney this brought some clarity to the documents I’ve been receiving lately.