I have never had that many people in my house but we have friends from church who have several renters and friends renting in their house. Since my husband used to be a renter with them I will explain their current set up.
The house has 4 bedrooms and 2 bathrooms on the top floor and a new bedroom and bathroom in the basement, so 5 bedrooms int total. The owners are in the master bedroom w/ bath. Their adult sons stay in one room when in residence and sometimes visitors are placed there. Then there are two rooms rented out to college students (so the place is empty in summer) who share a small bathroom with the sons/visitors. In the past 2-3 years they put in a bedroom and bath unit in their large basement, that gets rented out to another college student. The mom cooks and so 'board' is provided. They have 2 large dogs that eat everything. Renters are charged one fee for rent, board and utilities.
I don't know if they use a standard lease, but since they generally rent to college students (grad/undergrad and visiting scholars) who attend their church there is a general understanding. Just for my one roommate/renter I had a roommate agreement/lease. It had portions like a lease, but since you are sharing space there need to be house rules. I had things in there about guests, this included spouses (1 gal was a commuter who really lived in NJ), lovers, relatives, etc; kitchen usage; chores; smoking; quiet time; etc.
Another thing to think about is what kind of "service" beyond a room are you providing? Our friends from church provide a family atmosphere and a support network to university students and see it as a mission. I provided a short term flexible furnished rental to professionals who needed to be in DC.