As to point C, I think the problem you have is that you are following or associating with people whose opinions do not agree with your own. There are many opinionated people who are insightful, intelligent and interesting. Volume of posting does not always imply 'wrongness'. Similarly, regarding point A, why are you even connected to these 95% of people you don't care about? Perhaps if you curated or controlled who you connected to better you would find social networks much more valuable.
