help me to understand cams

Well im in the process of building a new engine in both my 67 Dart 408 stroker and 34 Rat rod 440 .30 over and other goodies. Anyways ive been reading and reading and reading about cams, and my head is about to explode. But ive learned a lot about cams and cam choices but i still am wanting to understand more about them and what makes them tick. For example what makes the chop in an idle? is it the lobe separation and lobe center-line? I understand to that rocker ratio and Cam lift is what determines valve lift. I just wanna understand more about cams cause it seams to me that the cam choice is the biggest effect on an engine. Thanks for the advice.