Might run a game one day where the Goblins are the children, the Hobgoblins are the adult men, and the Bugbears are the adult women. Maybe. It gives me some ideas for fleshing out the society if they have such major dimorphism, at least.
Bodyguard slave would work very easily. I think you could still make pit fighter a solid background - think of gladiatorial fights as similar to pro wrestling. Sometimes you want a bit of a change up to the standard formula. That's where team fights are in - suddenly you have to watch out for...
I don't use any Realms-specific things. I'll tweak bits of fluff to my liking as they interest me (I'll do the same with Eberron, but I'm not really interested in Eberron either), but I don't really go out of my way to find Realms information. The only setting I'd go out of my way to play in as...