When should I introduce rats in my situation?

[InvidiaBlue]

This will be my third question about my new rattie! lol

I just got a rat that is 1-1.5 years old from the shelter, and he is very socialized with people. Never bites, just occasionally "grabs". He was hand-fed from possibly a few days old. From what the shelter told me about his past, he and another of his siblings were ganging up on a third sibling who was sick (so maybe too weak to play or fight back). They were all kept in a cage that was obviously too small for three rats, about 2 cubic feet total. He is in a cage about that size and I am planning on upgrading to a very nice one soon. I want to bond with him and get him to trust me, and I also want to introduce him to two young rats so he won't be alone. I don't live within hundreds of miles of a good breeder, so the best I can do is take newly weaned rats from the pet store and socialize them as best I can. The one I went into has some babies that will be about 5 weeks old in a few days. Rats are bred in the local pet stores frequently so I'm not too worried about missing this litter.

So my main question is, should I bond with him first, and then introduce new rats? Or will he become too territorial over me or the new cage? Obviously introductions should be slow and supervised, but I want to avoid as much trouble and increase chances of success as much as possible. I don't know if rats become possessive about people, so it might be a silly notion but I couldn't find anything when I searched for it.

Second question is, will it make a difference what genders the young rats are? MM/FF/MF? With the assumption that spaying/neutering can be done to prevent babies.
Sorry, did my mental math in a rush. His current cage is 3.75 cubic feet, so I was off but even then a comparable cage is still stressful for three rats.

Thank you again Birbitt! Confirms my thoughts that they should prolly be boys. The quarantine will be stressful since my (literally rat phobic) mom barely tolerated me saving this one, and now she'll have to have two more, and in the living room no less, for weeks.