Hi, Anna--I've had a little training in it, but asked my hubby your questions, since he actually worked as a drug and alcohol counselor (paid staff, not volunteer). He said that clinically, no, alcoholism does not cause things like paranoia--until the final stage, when Organic Brain Syndrome (OBS) sets in.
But common sense says heck yeah, alcoholism certainly affects peoples' ability to deal with others. Obviously people say things when they're drunk that they wouldn't otherwise. But even when sober, the need to try and cover up can make them see accusations and attacks where there are none. Does paranoia lead to alcoholism? I shouldn't think so, unless the person was predisposed to it anyway.