Or even groups of people.
Yes, narcissism is something I have found to be related to the transit of Venus. I think it is because it is a subject more often related to how women view the world. Probably it's larger demographic are women manipulated by more powerful and virulent guys. So the discussion of it then becomes Venusian.
Yes, that's a point you could make. Like I have seen an article which was saying not everyone's a narcissist and one of the examples given was a woman who's husband refused to do the wallpaper or something. Yet another was a girl who said her boyfriend was a narcissist because he wanted to spend time alone.
Although I find the further you go into specifics. The people who become more professional and sometimes clinical, the more the examples become pretty harrowing. The ones with parents that were narcissistic, often mothers, are especially harrowing.
Just answered each one there.
Yeah, one of my thoughts about this whole area is that narcissism must happen on a sort of gradient and so, if I am looking to be able to spot the behaviour in my everyday life, the study of it must include a fairly wide range of behaviour. So right from the benign narcissist (almost harmless) up to the sociopath (sleep like a baby after they ran you over with a truck).
An interesting part of the behaviour pattern is that every behaviour links to another. So hypersensitivity, means you are likely to scapegoat to keep people away from you that you are hypersensitive to. Which means you have to lovebomb to an extent and perhaps gaslight the initial target. This sort of dynamic can lead to triangulation (using two sets of people against each other) and a whole horrifying dynamic and pattern of energies begins to show.
Being knowledgeable about such things I just think is useful.
We must speak in an subliminal language. We can't let THEM hear us!
ose-thay arcissists-nay re-aay istening-lay o-tay s-uay.
If you can speak pig, you will understand the Latin! 
I could write story after story about the ex husband/NPD. Instead I will just say that having been at his mercy and not understanding AT ALL what was happening at the time I've since learned more than I ever wanted to about this insidious disorder and the ramifications of it. Once you know/see it in action you can't unsee/unknow it.