I'm afraid that, at the moment, it'll break the continuity of attention, which I still have to strive for to maintain for more than ~5mn. My concentration ability has regressed, I'm afraid, due to a lack of practice.
Don't worry about it and don't beat yourself up over it, there are ways to improve your practice and incorporate it into your day. Practice well and you'll get results.
Regarding content and notes: while I sit, some of the proliferation is about...the practice notes!...."how am I going to report this?" or "let's remember; this, that and such happened, so the report will look like this", "what a gap between the experiences and a report" etc.
Aye, I know it well.

Note stuff like "planning thoughts", "questioning", "remembering", "effort", this is about seeing things clearly and a simple label will suffice.
Not great. I sit about twice a week, instead of the daily practice routine I had hoped to establish.
Even ten minutes of solid practice a day is better than nothing, this is about momentum and two sits a week just doesn't allow for this to build up. I highly recommend incorporating practice into daily life if you can manage it, remember that you're entire experience is made up of the sensations you're noting during a sit so there's no reason why this can't be utilized, particularly if you're pushed for time or have other commitments.
- the A&P is supposed to boost one's confidence and give important insights, right? I did have a confidence boost, but I didn't feel any wiser at all.
The A&P is "supposed" to demonstrate the fact that all phenomena arise and pass away, the increase in confidence is no more than a side-effect. I have no idea how wisdom "feels", all I know is that clarity and understanding of the nature of things increases with each Path. Insights occur but they may not be understood and integrated until further down the line, however something fundamental changes when we experience the transience of all phenomena for the first time.
- Are these two effects (confidence boost, important insights) supposed to be washed away by the dark night?
The map is referred to as the "progress of insight" for a reason, insight arises constantly as you practice and dark night is full of possibilities for deep, life changing insights. The shift in emotional tones to a more sombre mood is natural, but it is possible to navigate this phase skilfully and to learn a lot about what "you" are in the process.
I watched the first two Daniel videos at vimeo, and though I can relate to his descriptions of the pre-A&P stages, and some of the post A&P stages, but I'm definitely not the "technical meditator" he speaks of.
Ha! Don't worry about it, neither am I. Daniel's an exceptionally skilled meditator and his descriptions are the result of years of hardcore practice and retreats. He's qualified as a technical writer too so he tends towards super-detailed descriptions, but that surgical style is what cuts through all the shit of mainstream dharma blabber and demonstrates that this is all possible.
I guess I am in a Dark Night now. Looking back, some physical symptoms were quite clear during the rest of the retreat.
Now, psychologically (sorry..), I see more and more clearly the jerk that I am, and I become even more jerkier than I used to be, which is not nice at all for my wife nor for my self esteem. I also project on others my own jerkiness. And among my acquaintances, friends and family, I spot more and more possible dark nighters.
I overreact (and that's an understatement) more often and settle down slower. Seeing my bad temper arise in real time, "analyzing" it for what it is, and, despite that, *not* taking a wiser course of action, is very humiliating. No control over my self. What i've always tried to avoid...
Listen, you're acknowledging the fact that you
can behave in a way which can be construed as jerkiness, that doesn't make "you" a jerk. Being aware of these behaviours brings them into awareness, they become less automatic and the ability to objectify and observe them gradually removes their ability to affect you. The fact that you're aware of this is good work in itself and will allow you to examine these sensations, see what they're made of and see the 3C's in action.
When you feel these negative emotions, examine them and watch how they change. One minute you're angry, the next you're sad, then you're raging, then you're kinda o.k. etc etc, Look at how it's only through holding onto these emotions that they can perpetuate themselves, look at how this happens, don't fight against it, just observe and note accurately,
This stage will pass, just get more momentum going and maybe do a bit of samatha practice to take the edge off of how you're feeling for a while.