First off, you should not introduce the strays/ferals to any of your other cats until they test negative for FIV, distemper etc....if by chance one of these cats is sick you will run the risk of making your other cats sick as well. You just don't want to fool around with things like that. Once that is done then they can be introduced to your other cats.

If you want to bring them into your house because of the weather, etc...then make sure to keep them in a seperate area (maybe in a spare room or your basement or someplace like that). This will keep your other safe and it will also give these newbies a chance to get situated and feel more comfortable in your home.

I'm not sure about anything else, but I know that Kim, Jen, Kelly and several others know much, much more than I do about this and I'm sure that they will share lots more information with you.

Best of luck to you. --- Meg