I have a Ragdoll he is a 4yo nuet male and honestly the most amazing cat ever. He converts non-cat lovers to cat lovers, people that prefer dogs over cats to people that prefer cats over dogs. He is very daft and also completly non-confrontational when it comes to meeting strange cats. You would think this is a good thing but it means that if another cat/animal laid into him he would probably roll up into a ball and give up!
Because of this he is kept as a house cat, that and the fact he is so stupidly friendly that someone would probably walk off with him! He does go out for half a day in the summer/ better weather at weekends when we are around.
I'd suggest keeping the kitten in a seperate room, make sure he knows where the hidy-holes are etc to escape from the others if needed. Then I'd gradually let your cats say hello, through a wire mesh if possible. If you have one cat that is the non-dominant one start with that one. If you intend to let him out I wouldn't do so for a good few months.
Just be ready for sparks as cat meetings always take time!