"He'll quit drinking if it will make you happy"
This will be used against you in a future argument, he will remind you how he has given up so much to make you happy. This is called manipulation.
He can't quit drinking for you, or for his parents, or for anyone else. He has to want to quit himself in order for it to actually stick. And it's obvious he doesn't want to. Are you expecting him not to drink on your wedding night? On your honeymoon? That's alot to ask of someone who seems to enjoy the booze as much as he does.
You've already stated that he has told you to love him the way he is. So if you don't love him the way he is, right now, then don't marry him. If you do love him the way he is now, then get married and have a wonderful life together.
I think the most important question to ask yourself is, why do you think you should settle for someone who goes out all night and doesn't come home, and when he does blames you for all of his problems, gets violent, and breaks things? Why is it okay that he drives drunk, and puts his own lives and the lives of others at risk? (Imagine your future child in the back seat of his car while he is doing this) Why is this acceptable to you? Are you under the impression that he is the best that you can do? I'd like to tell you that you deserve more than this as a life partner. We all do, all of us here have come to this realization at some point in our journey... we just deserve more. Some of us took longer to realize this than others.
I understand that 'most of the time' he is perfect. Are you going to be satisfied living a life and raising a family with someone who is only there 80% of the time? As others have said here, it will get worse, it always does, so eventually that percentage will drop, and the "not perfect" percentage will rise.
I hope you don't feel obligated to marry him, simply because a few thousand dollars have been put down already. Take some time, there is no hurry. If he truly loves you and is worth keeping, he'll understand, and give you all the time that you need.