do the questions get harder as you go toward the end of each section? or is it pretty randomly mixed.

Well, it's a computer ADAPTIVE test. In brief, this means that the questions keep getting harder if you keep getting them correct, but they keep getting easier if you keep missing them.

So the answer depends on how you've performed on the test thus far. Once you get past a certain # of questions, the test gets a good 'bead' on your test-taking ability, and most of the questions will be right around the difficulty level at which they're hard but still do-able.