yes
No, Willie Parker was an offensive player. He was an NFL running back.
No higher than the ankles
That was running back Curtis Martin of the New England Patriots.
When the offensive team breaks the huddle and comes up to the line of scrimmage to start the play, the first offensive player to touch the ball is the center. The center snaps the ball to the quarterback and the quarterback will either hand the ball to a running back, throw the ball to a receiver, or run the ball himself.
To carry the football forward in pursuit of an offensive score
Halfback
Technically, under NFHS rules hurdling another player is illegal, though the foul is rarely called. Having said that... um, no, there are no rules that specifically dictate "how high a running back can jump." Presumably the limitations presented by gravity are sufficient.
running back,quarterback,offensive lineman,wide receiver,tight end,full back
Clinton Portis
Jonathan Dwyer is the running back for the Arizona Cardinals. He is a football player.
yes, it's call clipping or block in the back
No, an offensive player can make a "reception." A reception can be made by a wide receiver, tight end, running back, fullback, and in rare (trick play) scenarios, even the quarterback. An interception is made by a defensive player who "intercepts" the intended, eligible receiver.