lions are easy to keep, and the ones that look the best are volitans and radiata. they look basically the same but the radiata is alot smaller.
Wrong. Once they are eating well and acclimated, lions are fairly hardy, but that does not make them easy. Given the right setup and care, they are easy. Radiata get to 9 inches, not too much smaller. I would recommend them over a volitan, but both fish, given a large enough tank, are NOT the slow, passive fish most people will suggest. In a large tank, they are very active swimmers.
they basically only eat live foods, but eat about 1 platty every 4 days. you can keep anything with it that doesn't fit in its mouth! it eats all coral 
but you can always try.
Very wrong. Lions can be trained to take frozen and prepared foods, and every effort should be made to do so. Freshwater fish are NOT a good live food option, they have very different fats than marine animals need. Ghost shrimp are probably the most readily available, cheap option fo rlive foods, and will work to keep the lion going while you work on getting him to accept prepared foods. Lions do not eat coral at all. Ever. Devorative shrimp and crabs may be targeted, but snails, conchs, stars, and worms will be ignored completely. Lions typically are not added to reefs because they are high waste producers, and this complicates maintaining water conditions needed by corals. I kept a juvenile volitan in my reef until he was big enough to threaten the shrimp and fish, then moved him to a FO.
it may be better to get a friendly fish instead, but some cool fish you can keep with it are moon wrasses, foxfaces, triggers, and damsels if they are large enough.
Some wrasses will work, as will a foxface or tang (I'd go with a yellow or a scopas, and add it while the lion is still small). Triggers are not really a great companion--they tend to nip off fins during feeding, and some can just be nasty to the lions. Damsels--most will NEVER get big enough to be safe, and the ones that are aggressive enough to put up with a lion often pester the heck out of them. Bad choice. I'd go with either a tang (as above, the yellows, or a scopas would be fine in a 90), a butterfly, an eel (though they will go after crustaceans and of course you must secure the rock work very well--not great with a reef, but mushrooms should be fine), some of the larger wrasses, or, just let it be the only fish in there--much easier to maintain water quality.
