Curious since this was originally posted a few months ago, how it's going today!
Plan for the worst... hope for the best.
Layout these topics up front:
1) Food sharing rights
2) How bills are handled
3) When rent is due / if you don't pay? Fees? Time for eviction?
- Also recommend a rental agreement. Can be found online or bought at Office Depot / Staples.
4) Security Deposit
5) Living room rights / TV Room / remote control rights
6) Hours it's okay to be too loud
7) How long he is expected to stay

Drinking / Smoking /Drugs rules
Room-mates can be as bad or worse as any relationship. Communication is key... as in any healthy relationship.