There are several things to say here. One thing is you want to know where the chinchillas you are planning to breed come from. Do they have good bloodlines? If they are litter mates they should not be bred. A veterinarian or experienced breeder should be consulted to determine their breeding capabilities as well. Chinchillas must be fully grown before they are bred and other considerations such as size need to be taken into account or you risk having dead chinchillas. For instance a large male bred to a small female may produce kits too large to pass through the birth canal. Nutrition is another factor. I'm not saying you shouldn't breed but I am saying that you should be educated and prepared with the proper equipment and outlook before you attempt.
Here is a book that I recommend:
http://www.huggablepets.com/huggablepets/freebook.shtmlMore articles and materials are accessible to CBO members as well.
I do not recommend breeding pets that you are dearly attached to. Complications can and do happen. Do not breed if you are not prepared to deal with complications to the kits or breeders. Do not breed chinchillas if you don't know their genetic background.
As far as introductions I recommend separating the breeders but after the males have been introduced. Never have multiple males in a cage with other female chinchillas in the room or they may fight each other. Never put a chinchilla together without properly introducing them or they will most likely fight and injure or kill each other. Having multiple cage mates is possible but very risky.
Personally I don't have experience breeding but I do help breeders on this board on a regular basis and have seen many interesting challenges arise. Be prepared. It would be great if others who have experience can comment as well.