Start documenting. Now. 2 am and nowhere to be found. Behavior causing daughter anxiety. On paper you have a DUI and a job loss related to alcohol. Sounds like a good start to me.
I got the "we'll fight you" noise from my ex and his mom (had to have mommy there, pretty much tells you all you need to know). I told them to go ahead. Let the courts take a good long look at him on paper. Years worth of public intox type arrests, fines, etc. All pointing to a case for someone with a real drinking problem, if not an outright alcoholic. Shut that down real quick.
Quacking is part and parcel of the disease. No alcoholic really wants full time responsibility for minor children. Too much work, takes up valuable drinking time. That's just noise to try and keep us in our place.
If he shows up drunk, call the police. No matter what the outcome, get it entered into official record. Establish a pattern of drinking and irresponsible behavior.