This year as part of Christmas Eve dinner, I am making lobster risotto for 10 people. I've never cooked lobster before. Would you recommend whole lobster or do you think lobster tails would be sufficient to put in the risotto? I am planning on making stock with the shells--can you make stock with just the tail shells? I'm thinking that whole lobster would probably be cheaper as well...for risotto for 10 people, I'm thinking 5 pounds of lobster?

Thanks for any tips...