I would get one of the afore mentioned books 1st and get your tank stared to cycle before I would worry about that. I know pple who have kept lionfish and clowns together but I don't have any experiance with lions other than I 've seen them eat! lol. Thant and a friend of mine was stung by her's! That's a whole 'nother story! Let's just say the ER was clueless!
Remember .. patience .. gotta have a tank up running and ready before you can add even a little critter! .. There a a couple of the "big" sites that have "saltwater 101" news letters.. check it out....I thi nk About.com has one named just that! lol Also look into the profiles of both the fish you lited and see if they can be kept togther.....what ever you do make sure you have all the facts first!
sarah