No, this is one of the ways to get called for defensive holding. 5 yard penalty, replay the down.
It's called an interception.
This is a foul on the offensive player. The defensive player does not have to fall down in order to get a charge called
A defensive player may hold on to a ball carrier's jersey in an attempt to tackle him. However, if a defensive player holds on the the jersey of an offensive player who does not have the ball, that would be a penalty for holding. Likewise, if an offensive player holds on to a defensive player's jersey, that would also be called holding.
It depends on the team ... Coaches, offensive coordinators, and/or the quarterback call plays. On the defensive side there are formations called, the equivalent of plays for the defense. On the offense, if a play is called but the defensive formation is not conducive for that play, the QB can call an audible at the line.
The quarterback (QB) throws the football, the runningback (also called halfback and full back depending on their field position) (RB, HB, FB) runs with it, the receiver catches it and the offensive lineman blocks to protect the quarterback. There is also the punter in the special teams.
A pass completion.
It's called a fleaflicker.