Complete christmas ham newbie here.....I'm used to non-traditional bbqs on Christmas day.

We are responsible for the christmas ham this year, there will be approx. 10 of us eating, but with turkey and steaks and seafood too, so what size would I order? Have I left it too late? I don't even know what kind of $ that would cost?

And what do I need to do to it?

(They were either very brave or very stupid to leave it to us )