Lots of good advice here Trekkor. Tested and shots before introduction to the community, seperate room and litter box, and it's also a good idea for a separate feeding area at first.
Gradual introductions have always worked for us (we have three as well), and sure there will be some noses bent out of shape at first, but once they realize that they're all passengers on the same gravy train, it all works out.
We just introduced this one from the shelter to our 10 year old & 6 year old, and things are working fine. Good on you for saving one!
