Another strange question

I think the answer is no but I'm very new so I might be wrong. Is it possible to deploy a firebelly, in a group of maneaters that have scout as one of their rules?  The goal being to blast off my hellheart on the first magic phase. Secondly if you can even do this is it smart? I'm just trying out all kinds of crazy ideas now to see what might work. Thanks!

The answer is no. Only characters that have the scout rule themselves can join scouting units.

Otherwise there would be overpowered characters running around in your backfield turn one 

I figured as much. Same go for vanguard?

Yeah same goes for vanguard, it will say in the special rule if characters get it too, like they do when they join a skirmishing unit

Also, unless this has changed, maneaters cannot be joined by characters except Golfang who is a maneater himself.

Nope, Maneaters can be joined by any non hunter character -  after deployment it doesn't even matter if they had scout or vanguard (might take a few turns to catch up). Most of the rules don't transfer to the characters (Stubborn being an exception)