Rugby players wear boots.
You can wear soccer cleats to play american football but it is less than ideal. Soccer cleats do not have a stud on the toe of the cleat like football cleats do. This make it much easier to run, cut and dig into the grass. Most football cleats are also higher and more supportive than soccer cleats. Although if you are a field goal kicker/ punter or kicker in American Football - they all wear soccer cleats. Basically you CAN wear soccer cleats to play American football but you CAN NOT wear American Football cleats to play Soccer.
soccer, football, or lacrosse cleats
No, they have different cleats
Yes you can as soccer cleats are versatile cleats, but i would recommend football cleats as they have a higher ankle providing more support.