I can only answer a few of your questions. On synchronized transmission you do not need to come to a complete stop when up shifting or down shifting. As far as forward to reverse/reverse to forward you do not need to be stopped, BUT I would not let the clutch out if the tractor is going in one direction and the transmission is going in the opposite direction. ie rolling backwards and letting out the clutch to go forward. Doing this could result in taking the face off the clutch. The free play is at the top of the clutch. On my tractor it is .5 inch (you would need to check your manual for you tractor). You need to have free play, so the clutch does not slip.