Wii in groups is ok, but almost all 360 games have online only muti player so for that a LAN set up would be better.(google it)
My advice is get some arcade machines in (can be mamed, but there are multi carts that work)
Avoid the alcohol as you need a special licence to sell it.
You could go down the retro route and have a few older consoles set up
Do something smiler already2) If you live with your parents, do you think they would let you come alone to a place like this to meet your friends?
There is a pub localish to me that has a load of arcade cabs and is used as a meeting point for gamers (and has games nights)
If people are going to pay for such a thing you will need a entertainers licence.3) If you would be willing to come check it out, how much would you be willing to pay for something like this?
Its best to be cheap and have regular tournaments where a small prize can be given, but charge them a small fee for taking part