@Fred Hess I think @Joey Sargeant makes some good points. So, quick down and dirty here are my insights on your questions:
1. Friends or not, have a lease. It needs to lay out expectations upfront. Unfortunately things do happen and it is always better to keep business as business, no matter who it is with.
2. Rent ranges like Joey said can be a simple search on craigslist to determine what market rates are. Otherwise, you honestly can charge what you want. But again, to keep it as good business I would not greatly exceed market rates.
3. Have everyone purchase their own food. Individuals might treat it like dorm rooms and keep snacks and personal items in their rooms in order to "safeguard" them.
All in all, this is an extremely smart idea to do for quite sometime. Even when you move into another home down the line house hacking is a proven way to continue to perserve capital for future investments. Best of luck to both of you.