So, I have become more selective.

signed contract for 125k 30days for closing .....

My name is Geoffrey and I just signed up as BP Pro members couple weeks ago because I really want to know more about real estate investing.

On a Non-QM loan, you can finance the property in the name of the LLC but must sign a personal guarantee.

Tenants are given a bank account number at a local bank (I have one account per building, exact rent amounts are unique within each property to avoid confusion with deposits), and as a condition in my lease (which they signed), they are REQUIRED to make payments to that account. 

Not just from your buyer side of the transaction.If you're only doing one transaction, it's probably not worth getting an EIN.You can have the check made out directly to your name, you just have to remember to deal with it during tax time.If you plan on doing more of these and other transactions, then it might be worth getting into a DBA and/or EIN.I go through this all the time when I sign up with vendors to do BPOs.

Can I sign a regular tenant lease with them, or do I need a roommate specific type of lease?

Parental co-signing is possible but not probable.Has anyone been in a similar position?

Otherwise I usually just track down the previous owners and get them to sign Quit Claim Deeds to me.

I agree with Andrew - don't have your new tenants sign a lease until you've had some time to experience them as tenants.