Ya know, it's funny.. I work at a vet's office and we don't deal with small animals but my boss said he would neuter the rats for me.. I'm just really terrified of doing it. They're tricky on the anesthesia and I'd hate for something else to go wrong with any of them. I will definitely work on introducing them. I was actually just looking at cages for after they are all settled.
You know your boss best. Has he done /any/ other small animals? If he's had no experience doing rats, I'd look around to see who does. Neutering is the least invasive of the possible surgeries for rats. The incision is about the width of a thumbnail if that. I've had a problem with abscessing with my hairless boys, but a follow up trip to the vet for draining and AB's and they were fine.
As for whether or not to do it, different people have different opinions. Four of my seven boys ended up being neutered for different reasons. My two hairless for hormonal aggression. My big man Black Pete because he temporarily lost his mind when he took over the cage after the death of his best bro....the neuter calmed him down considerably. I neutered my last boy because I'd just gotten girls. I've heard too many stories about randy girls getting in with boys by squeezing their tinier bodies through impossible cage bars; or a family member accidentally putting a rat into the wrong cage after playing with them, or just something in the water.
However many folks say neutering except in cases of extreme hormonal aggression is unnecessary and cruel. Me? I think it's cruel to keep them isolated because a miserable soup of raging hormones or fertility keep them from interacting well with other potential cage mates.
If it were me, I'd go through the intro process with hairless boy and the baby boys and see if they can get along. The intro process can be as little as one session, or as long as a couple of months of every day working on it.
If they can live together, then it's a matter of whether they get hormonal later or if you're willing to deal with keeping them completely separated from the females.
And, good tip Breyer, about freezing the bedding. I forgot about mentioning that. I'd freeze any store bought bedding for a couple of days before use. Prevention is less painful than the cure and all that.