Your parents are totally in the right.
As long as you are in someones house - parents, dormmates, ect, you have to abide by rules. It's very obvious you are an irresponsible person that cannot make rational decisions. I do not fault your parents at all for the course of action they've taken.
They are doing the most reasonable, intelligent thing in light of your utter stupidity and disregard for the law. My advise would be to abide by their rules, because if you don't, your headed for a few decades of major fail. Having DUIs AND being underage is not a combination for rampant success.
As for the beers and driving question:
If you are drinking at all, do NOT drive. No exceptions. The law can and will usually have probable cause by poor driving to pull you over. If they have probable cause for a traffic stop, you will probably get charged with something even if it's not a DUI.
Back from the dead, I'm afraid.
