Dark night (dukkha nanas/third vipassana jhana) doesn't have to be intensely negative. If you have good karma or are well practiced then it can even be enjoyable. The hallmark is the widening of the attentional field, the loss of focus at the center, the increased emphasis on the disappearance of phenomena, the experiential insight into emptiness. The kind of visuals you mentioned are typical of the A&P nana, so it's possible that you are experiencing the shift into dissolution, but it's hard to diagnose with limited information. If you want to get more clarity, keep practicing and see if the experience repeats and/or evolves.
 

 Yeah again, different people will experience different levels of intensity during A&P at different times depending on conditions, and there is a huge range of phenomena that can occur. I don't experience much visual stuff compared with others, hopefully someone else will chime in.

If you want you can intentionally cultivate the more energetic aspects of the A&P by focusing on some kind of pleasant physical sensation in the body, e.g. sensations of tingling, vibration, touch, warmth etc. or repeating a word such as love or bliss and feeling for some warmth in the heart area. Allow yourself some time just to enjoy the sensations of being in a body, breathing and see if the pleasant feeling starts to enlarge or intensify. No need to force it, but it will happen naturally because the body has an incredible ability to generate physical feelings of pleasure just by relaxing and letting go, and cultivating a grateful/happy/luxuriant mind state.

Point 4 you mention sounds like an experiential insight into the anatta/not-self characteristic, which can be experienced as a kind of agencylessness or automaticity, or even depersonalization at the extreme. Sometimes that can be unnerving and a more physically grounding practice with greater awareness of the body can help with that as well.