You should ask the to sit down on the toilet and pee that way. That is the proper way for both girls and boys, but no one really bothers to teach boys the proper way to pee.
Nope. Most times the dribble on the seat occurs from your guys being half awake, not paying attention or them TRYING to hit the seat. They can prevent it.
It depends on how intoxicated they are (if so, then yes), if they have an erection (if so, then yes), or if they are just to lazy to aim at the toilet!