Don't know about now but the rule was 10 yards.and illegal in high school when I officiated, should be in the NCAA also, IMO. In high school it is called using a substitute to deceive, and also you have to be within a certain distance of the ball before the snap.
No, coaches from the opposite sideline aren't necessarily going to catch that. The players on the field should damn well catch it though.They all were in bounds talking to the coach and 10 ran to the ball and one just stayed by the sideline. Coaches need to pay attention.