How will my alcoholism effect my teenage son?

In many ways. Your child may feel neglected by your drinking or embarassed by you. He may choose to follow your example and begin drinking himself. There are many self help groups for families of alcoholics that he can turn to for support. The fact that you have recognized that it may affect your child may be a good first step in getting control over your drinking.
It depends. It is unclear whether you are referring to yourself as having the problem with alcoholism, or if your son is the one with the drinking problem. If you are referring to yourself, your son is at risk for substance abuse problems if you are an alcoholic. Your son may benefit from a support group called: ala-teen. If your son already drinks, i would seek out treatment for him asap. Good luck.