My first thought is will your landlord approve of the extra tenants in your apartment for that period of time? You should check your lease to make sure that you won't be in violation and wind up all being evicted. Some places have strict restrictions on how many people are living in a 2 bedroom apartment.
My other suggestion would be to right out a contract of sorts detailing the length of time these people will be living with you and what their obligations will be and have everyone...you and your bf and roommate included...sign it as an agreement.
This will protect you and bf in the case that things go sour...and it protects the other people from you kicking them out before the agreed upon time.
As for keeping to yourselves, I suggest that you just have a chat with everybody and let them know that you mean no offense but that you prefer to keep to yourselves just because its the kind of people you are.
I hope everything works out for everybody.