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

I did ask them about any history of the sewer causing any problems and he said no.

There are ways to provide a 2nd mortgage for a home purchaser, such as a contractor with poor income history(on paper) and have the payback at 25%+ in 18 months.

I have rent history on all 3 ranging from 1 - 4 years.

It's all about what type of investment you want to pursue, your credit history, availability to pay the loan, etc., etc.,   I'm assuming you don't have the $ to buy cash, since you are asking here how to get started.  

IMHO decent public records data and transaction history.  

Aside from providing the basics (ie. listing tool to get the property published to 10+ major sites, scheduling tool to schedule viewings, tenant screening with comprehensive applications -- pulled reports from TransUnion, which include nationwide criminal background checks + credit checks + eviction history, digital lease creation tool, rent collection tool, and maintenance tracking tool), some services also offer your tenants additional capabilities which makes it an easier sell on your end when getting them to transition over (ie. their ability to report on-time rent payments to the credit bureaus; this can create an added incentive for making sure they pay that rent on time).

Yes, I am currently enrolled in college here a ton of great music and history. 

The owner seems to have pretty extensive history with the registrar of deeds and I just am wanting to be sure there are no other liens out there.

I was not able to find an occupancy rate history.- The current median rent is $1267 which is my sweet spot.