Well in terms of insecurities, I know that when I'm out with friends, drinking acts to relax me a bit more than normal I suppose. I think alcohol in my mind is associated with being more relaxed and comfortable in certain social situations.
However I do not feel overwhelming or even noticeably uncomfortable in the company of my friends, but alcohol does seem to function to increase the quality of a night out for me.
In terms of noticing how pissed I am, I can tell up to a point, but after that point I just seem to switch to a kind of autopilot mode in which I am concerned only about drinking. It's like tunnel vision, all other thoughts that usually cross my mind, like money, how I am going to fell, what time it is etc, these just completely disappear, and I just focus on drinking more and more.
I have also tried to separate out my drinks with a pint of water between each one, but that approach has deteriorated rapidly.