Like the others said, I've never heard of a communal mantid.
In some cases, you can keep more than one together, but there's always a high risk of cannibalism. I managed to keep two pairs in a 10-gallon tank but I wouldn't recommend it if you're not prepared to lose a few specimens.
I believe the Bug Zoo in Victoria BC has a few communal enclosures, but they're very large and only sparsely populated.
To answer the question about flight, generally speaking males are capable fliers and females are not. Some females can fly decently enough shortly after they mature but before they become noticeably gravid.
If your emperor scorpion stops eating, don't panic.
Be nice -- you were a noob once, too
"Never ask an engineer to explain something, because he will."