1) Yes there IS a difference, and significant one. To see it, just plot arty mission, then try to shift the target point with HQ and with FO and you'll see for yourself
2) Right-click changes facing, so it has more sense for tanks, but... IIRC unit has better chance of opfiring or just spotting enemy if it is facing to him. You can manage to sneak pretty close to unit facing in the other direction, but good luck if they face you.