Art Gallery?

I have been playing around for a while with the idea of opening an art gallery in south Bristol. Some of my questions are:

• If it were possible to open an art gallery what would the business model be?
• How would it generate revenue? It is possible that some of it would come from commission on sales, but how much commission can you charge on these things?
• Would a gallery make money if it also had coffee/food?
• If there was a computing/website consultancy tied in do you think it would work?
• Where do you think it would be best to site it?
• A web based gallery would be cheap to run and might make money as well as a physical space. Having both would be a good idea.
• Who are the customers, how much income do they have? How much can they afford to spend on art?
• Is the gallery a contemporary space or traditional? Or is it both?
• Hands-on courses/demonstrations would be good