What should my weight target be? 19 year old, male, 6'1/6'2, medium frame...

Weight: It should be about 170 to 175 according to the charts.

Body mass index: Use http://www.Nhlbi.Nih.Gov/guidelines/obesity/bmi/bmicalc.Htm to calculate your body mass index. Normal weight for 6'1" is 140-189#, a bit more for 6'2" regardless of frame size. This also doesn't take into account body composition. You don't want to be skinny fat. In other words, 189# of muscle is better than 140# of fat, although 140# of muscle is just fine whereas 189# of fat isn't.