RE: 1 eye or 2
Both open for the past 20yrs, makes a HUGE difference, imo. When I started I shot one closed....so glad I switched. Teaching my son 2 eyes open from the get go and so far he's doing well. If you are having trouble, just practice alot - you will get used to it, as awkward as it may seem at the start. Yeah, you might get a flyer now and then that misses wide - but once you get it down, you will be happy you did. I too feel eye dominance makes a HUGE difference in two eyes open. If your dominant eye is on the off side, you will fight it constantly.
Mike