Can caffeine will deplete your body of vitamin b; is this all?

Yes & no: Caffeine acts as a diuretic & makes you urinate more. B vitamins are water soluble so you might potentially lose more b vitamins while you urinate. But realistically, this loss should be negligible, similar to if you drink a lot of water and have to pee it out soon there after. Alcoholism is different in that alcoholics tend to drink alcohol to exclusion of most other nutrition & vitamins.