1) toss out all center of glass ratings. They are worthless and serve no purpose other than for unscrupulous salesmen to mislead or confuse you. NFRC tests total unit.
2) SHGC is solar heat gain coefficient. You live in a climate where you heat your home far more than you cool it, so you want to take advantage of some of that passive solar heat through your windows, but balanced of course with a good u value ( for insulating).
3) If Anthony serves your area he would be a tremendous resource. You can click his get a quote button to contact him.