Thinking about the Shirt

Knowing my preference for comfortable clothing, I purposely left off the front and back vertical darts when I traced the shirt pattern. I have reconsidered. I need to know how accurate the software is. Well, to be honest - the quality of the measurement taking.....I also need to know how this shirt will fit if I intend to manipulate darts to create other styles (I do intend to). The button placement looks off to me. Shouldn't there be a button at the bust point to hold everything together when you move your arms? And, what is up with the 5/8" seam allowance for the collar and stand? All this before I have even sewed up the muslin......