This sounds like an absolutely fabulous idea! Book club and luncheon once a month! I am not reading nearly as much as I'd like to these days, and this would be the perfect way to get more reading in and make some new friends. Maybe a names in a hat deal for the book choice? Everyone puts a book in and we can work our way through them all until we empty the hat, then go again!
I agree that you shouldn't have numerous books around in the book club, but another idea for you're book club is to have 2 or 3 books with a similar idea/theme/genre, and have the group compare and contrast the two books. Talk about how the authors approached things like conflict, description, character development, etc. differently and how it enriched or detracted from the book, or the reasoning for why a certain technique was more effective than others, or why it could have been improved.