It depends on how well I know the people, the adults and the kids. If I don't know them well, then I will greet them at the door, otherwise I let my son meet his friends and off they go.
As for food, at 12-13, my boys know how to fend for themselves. They know how to cook simple meals, and when they have friends over they like to do their own thing. If I have a family meal planned, then that's what we'll do, but usually it's a Friday night and I'm fine with taking it easy and letting the boys scrounge. They know how to find what they need and clean up after themselves. I never fix breakfast. They're better at it than I am. Also, I work hard as a teacher, and if I'm home, I'm in pajamas. My house is spotless because I have control issues, but I like to be comfortable. Everyone who knows me has seen me in pajamas. I don't see it as a character flaw.
I guess to answer your question simply, I don't cater to my kids friends much at all. I make sure there is food in the house for them. I tend to their cuts and scrapes when they get hurt. I get them blankets and pillows before bed so that they will have what they need to be comfortable sleeping. Other than that, they are usually outside getting into adventures, watching movies or playing games with us, or working on building a new computer together.