I personally have known two people who were diagnosed as paranoid schizophrenics. Both were male, both were about my age (I was in my early twenties when I met both of them....I'm 30 now). Both had similar symptoms: delusions, hallucinations, fits of rage, destruction, etc. Both had substance abuse problems. But that's about where the similarities end.
One of them continues to self-medicate (he smokes pot on a daily basis) as well as see a Psychiatrist and takes prescription drugs. He's also on disability for his mental condition. He pretty much keeps to himself and has a few friends that he hangs out with. He lives with his parents, though he has expressed interest in living by himself (which I think he is capable, but would need some help).
The other person and I became casual friends. We spent alot of time together for over a year. Then he became to isolate, as his symptoms grew worse. (For a time he was on medication prescribed by his psychiatrist.) Eventually he stopped taking his medication and his symptoms became acute. He was hospitalized several times over the course of the next two years. He would stay with his mother when he wasn't in the mental hospital. The same medications were no longer working, so he was always on different ones. Last I heard he was back at the hospital. I haven't spoken to him in about 2 years or so.
There are treatments, but the results vary. I've heard many stories about medications working temporarily, but not long term. There are a variety of medicines that can help though. Some are sedatives, some anti-depressants, or a combination of the two.
As far as I know, it is something that lasts a life-time. There is no "cure" but it is treatable. And as you can imagine, it's a very difficult thing to watch somebody go through.
edited for clarity