OP, you are wise to quit drinking; don't listen to anyone who tells you otherwise. I cannot think of one single person I know whose health has benefited as a result of drinking alcohol. In fact, almost every single person I know has been negatively affected by alcohol consumption (either their own or someone else's), in one form or another.
One reason I do not drink is because of the negative effects it has had on most of the people close to me. My late father was an alcoholic, and my mother and brother are too. It has been demonstrated that alcohol is toxic, and a detriment to public health [1], [2]. In fact, according to [3] alcohol was the fourth leading cause of preventable death in the US during 2014. I don't understand why everyone brags about excess drinking, IMHO it makes you look dumb.
Even if it weren't for all of these terrible consequences of alcohol overconsumption, I still wouldn't drink it. I don't like feeling drunk, and alcohol tends to make me me lazy.
OP, to answer your questions.
1) Yes, there is almost always an element of schmoozing in many business settings. I don't really look at it that way, I prefer to look at it in terms of relationship building. That said, I will not have a relationship with someone who pressures me to drink, regardless of the situation. It is that simple. Since you sound like you're in law, I would imagine the peer pressure would certainly be higher. However, if I were you, I still wouldn't want even professional relationships with people who pressured me to drink.
2) Since you say
"He will still frequently go out on Friday and drink 10 - 12 drinks and black out. When he wants to be, he is incredibly rude and insulting when he drinks."
it sounds like he is definitely alcoholic, since his behavior is negatively impacting his health and those around him. Based on his behavior towards others alone, he should limit his alcohol consumption
Personally, it sounds like the person you refer to isn't much of a friend. IMHO, someone who pressures you to drink and/or acts the way your friend does probably isn't a friend.
It brightens my heart to see threads like this, when excess drinking is so often glorified.
References
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[1]BBC:
http://www.bbc.com/news/health-15114325[2]NIH:
https://www.niaaa.nih.gov/alcohol-health/overview-alcohol-consumption/alcohol-facts-and-statistics[3] Stahre, M.; Roeber, J.; Kanny, D.; et al. Contribution of excessive alcohol consumption to deaths and years of potential life lost in the United States. Preventing Chronic Disease 11:E109, 2014