Offence in motion before the snap changes things. He has to maintain coverage on a receiver that might already be full speed on the line of scrimmage at the snap
you can score a single by a kick into the endzone. It's to encourage returns on punts, kickoffs and missed field goals. Think of it as the end zone is always an active scoring area with anything to do with a kick into it. That includes missed field goals. Strategy of field position vs surrendering a point becomes more important towards the end of games. More favourable field position (but giving up a point) vs returning it to the 10 or 15 becomes a gamble at times.
The Receiving team can also catch it in the endzone and punt it out themselves to prevent a single point. At that point the opposing players can recover it and kick it back in the endzone for another single attempt. Once in a blue moon those endings happen in tie or 1 point game. Really exciting ending
