I had the big kinds of lionfish - volitan and mombasa. Tank size, of course, 90g. Larger would be better.
Both kinds are reef safe, but they like to rest on the corals, such as chili or black sun coral, with no harm done, just a gentle touch by fins.
Will eat the shrimp or a small fish or not - tricky situation. While the soft-shelled shrimp is a very good candidate to be eaten, the blood shrimp has much better chances, for a while.
Lionfish may not eat them for a very long time (1.5 years in my case), then one smaller fish and a blood shrimp disappeared. But 2-2.5" percula clown, damsel, chromises are alive and well in the same tank. All were there since their childhood.
Lionfish grows very fast - in a months, not years.
Very serious problem is with some lionfish, that may refuse to be weaned to the frozen food. Starving it for two weeks without food, offering only the thawed food, may raise the strong family protest. It's also a situation to avoid.
Not much help, but lionfishes have a great personalities, and are well worth keeping, if you have a large tank and can give away the tankmates at risk.