Anthony,
The agent selling you the house should be able to give you a blank lease contract that you can use. You can also google and find a simple lease contract online. Just make sure that it is your state specific. If either of those options don't work, a local property management company might be able to give you one for a small fee. Most people won't expect anything fancy with renting out rooms.
Get the people to fill out a simple lease app(find on online), and a bank statement. If they don't have a bank statement, look elsewhere. It means they don't have good enough credit for a bank to allow them to have one.
To run credit, I have people run their own credit on Experian.com. It is free and since they are running it themselves, it does not bring down their score. Between the credit, bank statement, and a prior landlord reference you should be good. In my experience, people with good credit want to keep their good credit.
If the credit is bad, watch out! Call the landlord references and make sure the reference is the owner of the property. Bad tenants have a habit of listing their friends or parents as prior landlords. If someone has a story it is not a good sign. Good tenants don't need a story.
Hope this helps.
http://www.experian.com/consumer-products/free-cre...