4- link vs. Triangulated?

Ok.. I guess I have a couple of questions. I pretty much understand the concepts and function of the set up. But, if I go 4 - link ,then I have to use a panhard bar. What is the formula to calculate the length, so that there is minimal side to side movement? If I go triangulated, is there a min. length of the bars, or is it all in the angle? Bags over axle, or mounted on ladder bars? I realize this is a newbie question and probably answered before, but any info gets me that much closer.