And to add to it.....when a section line is not horizontal or vertical (let's say 30deg off either), the resulting section view is not aligned horizontally or vertically either. When drawing a rectangle for cropping purposes afterwards, it is no longer "square" as well. Any thoughts?
I'll try to take these one at a time. You can add relations between a section line and a model plane. I do it all the time. Sketch your line, then click on the line to highlight it. Hold down Ctrl, scroll through the tree to the desired plane and select it also. You should be able to set a relation (probably collinear in your case). Oddly enough, if I select the plane first then I can't set a relation; I have to select the sketch element first.
I'm fairly confident that a Section View will always be created perpendicular to the line, but since I don't believe I've ever created one that wasn't horizontal or vertical I'm not absolutely sure. If I'm wrong about that I'm sure someone will correct me.
I'm not sure I understand your last question. Are you cropping your section view?