@Nathan Gasti
I would, without a doubt, request a copy of the rent roll and the property expenses from the past 3 years.
The rent roll is an accounting ledger that will give you a better idea as to when the tenants pay rent each month, how much they pay(hopefully it's the full amount), any amounts that have yet to be collected, security deposits, and any other miscellaneous fees.
The property expense report will give you just that, the expenses of the property. The reason you'll need to see accurate expense is so 1)you can properly calculate your NOI, 2) you can see if there are any deferred expenses and 3)you can get a better idea as to what kind of existing owner you are dealing with.
I akin detailed accounting in a property to a used car owner keeping his original service manuals and service receipts. An owner who is diligent in keeping his/her income and expense accounted for is, more than likely, and owner who takes pride in his/her investment. Hope this helps