To answer the second question: professors at most universities these days take teaching evaluations fairly seriously -- not necessarily one by one (although we are human beings and a piece of seemingly undeserved criticism can stick in our craw as much as anyone else, if not more so because there is no other aspect of our job in which we are as openly criticized) but certainly on average. Probably 95% of professors are or were in the situation where having numerical scores below a certain threshold creates trouble for tenure and promotion cases. (And once you get into the habit of caring about evaluations, it's hard to break. A colleague of mine is a full professor but is just as concerned that her evaluations stay high as I -- an untenured professor -- am.)
Most departments these days have a sentiment that although great evaluations are not necessarily highly correlated with great teaching (in part because it is not so clear what constitutes great teaching!), really poor evaluations probably mean that the instructor is doing something wrong, not necessarily content-wise but in the way s/he is relating to the students.
I am sorry to say that a lot of professors these days might well conduct their classes in a way that they believe in their hearts to be more educational for the majority of the students were poor evaluations not such a critical issue.