hello and welcome to the forum!
new introductions should always be done slowly and carefully to get the best results. A lot of people have a tendency to just put the cats together and let them work it out- sometimes things work out fine and sometimes they don't, so its better to do a slow, planned intro to increase your chances of success.
You should start by keeping the unfamiliar cats in seperate areas of the house. Since you'll be living with roommates, I'm guessing that there are at least 2 bedrooms. I would suggest starting by putting your cats and the new cat in 2 different rooms. Don't give either set of cats access to the rest of the place yet. Since this is a completely new place for all cats, neither one will feel that it belongs to them, and this is good.
Then you can you can let your cats and the roommate's cat out to explore the rest of the place at separate times, a little at a time. This will give them a chance to become familiar with their new home. It will also give thenm a chance to leave their scent in some places. The cat's will be able to get used to each other's scents without meeting directly.
From this point on, you can pretty much treat the situation like you would if you were introducing a new cat to a home with established cats. There's a lot to this, so I won't write it out, but instead refer you to some good articles on the subject.
The most important things to remember are to take things at the cats' pace. Move on to the next step when you feel that they are ready, rather than adhering to a specific schedule.
You want to avoid fearful and aggressive meetings. First impressions are important, and a bad experience can affect the relationship between the cats for a long time.
You may also experience redirected agression between your 2 cats. The scent or sight of the new cat may cause your cats who are usually friendly towards each other to act aggressively towards each other instead, so be prepared for that.
I hope that helps some. Good luck and let us know how it goes!