Re (2), I always soft-block (block and then unblock) rather than unfollow, mainly because I view my twitter feed as a collection of friends, and I'd rather "terminate the relationship" than make it one-sided. If I want to preserve the relationship but find them annoying, I'll mute them.
I do this two, but I have sort of two mental categories. The people who only occasionally pull me in. I just mute or block then unblock. Then there are the people who consistently try to pull me in and view it as their duty to do so. Those I just unfollow, it's not worth the effort to keep them in my feed.
