There is no age of onset although it does seem to occur in older men.  Smoking can contribute to the development, I'm not sure about drinking though. I do know you have a higher chance of bladder cancer if you drink.  Symptoms can be swelling of the prostate or an increase in the PSA as checked by blood work.  This is also why doctors do prostate exams by rectum.  If the prostate feels nodular, they will start doing studies to see what is going on.