Help for the future!?

Me and my friends will be going to Calgary or Edmonton for university and jobs but there are some problems one of my friends is going to the a university in Calgary, Edmonton or Saskatchewan for Veterinary school to get his Ph.D, I will be either joining in a branch of the army or be going to a Alberta university for computer science and/or computer engineering. Where as my other friends will be joining the police colleges of Alberta or California but he is Canadian do you think he could be a cop in America? Also he has done drugs about 2x nothing major just weed but I am afraid he will continue because his older brother is doing it with him and if so the fields me and my friend will be working in we can't have a guy with drugs in the same apartment as us so is there anything someone can do to help please. Maybe someone with a similar experience?