I am the alcoholic in my marriage so I'll respond for me
1) As the people here will tell you, you have to stay in your lane and deal with what you can control. Al-anon seems like a good suggestion.
As for AA, we all come to it and experience it in different ways - both initially and then during. For me, there were too many people in the room, and it made me nervous. At my first meeting, I managed to self identify as 'new' and 'alcoholic' not knowing it would cause the more senior members to flood to me after to offer phone numbers and conversations. It was overwhelming to say the least. I navigated that and managed to get to meetings, and found a small group of quieter women. I wasn't and still am not much of a higher power person, and that's never been a problem. There are certainly people who are very 'high' on the program and perhaps seem a bit 'preachy', but like everything else in AA you take what you need and leave the rest. Some of the harder parts of AA (for me) are way more internal than external. When a speaker or a step discussion moves waaaaay close to home and hits a lot of nerves. I can leave AA meetings pretty shaken, and usually need to follow up with my sponsor to figure out what to do with the ugly feelings that can arise (shame, embarrassment, etc)
That said, AA is not for everyone, but those who find that do so after really trying it. I know people using SMART recovery, Rational recovery, who go to the Gnostics chapters.... etc. Some people prefer one to once counselling. It depends on the person. but the commonality is that the person is actively seeking a new recovery program and demonstrating deep commitment.
2. Agree, secrecy is the best friend of the alcoholic. I don't have any hard and fast facts - but I again recommend al-anon. You are a person too, you need to talk. I imagine there's a lot to talk about.
3) Social situations is a tough one. This is a road you can draw a lot of boundaries on. Understand that you cannot change the behaviour of the alcoholic, that is within his control only. So if you do make plans to bring the alcoholic out, you must also accept any and all alcoholic behaviour. Which seems like a pretty raw deal, right? A couple of years of sobriety and my advice to you is not to set yourself up for disappointment and failure. You'll be angry, you will want to confront him, and nothing will be solved.
You didn't ask but here's the thing - alcoholics get sober when they want sobriety more than they want to be drunk. There are no rationalizations, there is no real criticism of the method we take to become sober. If one doesn't seem to gel we find another. We use multiple methods at the same time (for me, AA, SR, books on addiction, counselling, regular medical apps with dr, journalling, and meditation). When we want it we stop at nothing. When you see that level of commitment, and behaviour that is non-erratic for some time, then you will know what's up.
Wishing you nothing but the best