I may not be the fountain of wisdom you were hoping for
When ever I have introduced a new kitty I just turn the new kid loose in a part of the house away from the old kitties. The new kid starts sniffing around and checking the place out. The old kids are happily hanging out elsewhere without a clue. At some point they end up meeting. New kid gets hissed at, I comfort the old kid who is probably on the verge of a break down due to the new discovery, the old kid often runs off in a huff and then I comfort the new kid. Give everyone lots of attention and by all means don't make a big deal over hissing. When they don't get reactions to their hissing fits they tend to calm down. I always start with kittens. I find the kittens are pretty tough when it comes to being hissed at. I'm not too sure how new addition adult cats react to this though. Simply put, I let them speak their peace to the new kid...let them know who is top cat so to speak. Now if claws came out then I would step in right away.
I would like to note that everything I have read on the subject doesn't agree with my method outlined above. I still stick with my method since it has worked well for me. I seem to have well adjusted cats who have not suffered physical injuries.
As for when to let kitty outside... I thought you knew me better then that!
My answer is never
I have no words of wisdom at all on when, how or why to let a kitty outside. My only guess is to at the very least wait until kitty has adjusted to his new/once old home again. I have heard of stories of kitties running off only to end up showing up at their old homes. I would think you might need to give things enough time for kitty to think of your house as home again.
As for how to keep "the other peons from revolting"... keep their schedule as normal as possible, keep their food the same and give them lots of love and attention. They will hiss, holler and moan, but will eventually get over it
Good luck and keep us posted!