Yes.
It is illegal to impede the progress of any player, regardless of whether the player is in possession of the ball, by sticking your leg out and attempting to trip them. The penalty is 10 yards.
No. Tripping by a blocker for the ball carrier or by a defender trying to tackle the ball carrier is illegal and is a 10 yard penalty.
Tripping
Yes
believe it or not it's just called tripping
It is a ten yard penalty - Vikings vs. Steelers 10/25/09
The maximum distance that can be given as a penalty in American football is half the distance to the opponent's goalline; for example, if you were on the 15-yard line and received 10 yards of penalty, the maximum you could gain is 7.5, or 8 yards rounded.
Pittsburgh and phillidelphia, November 10,1940
There is no penalty for that
There is no evidence that such a penalty exists in any football league currently.
Boarding Charging Checking from Behind Cross-Checking Delayed Penalty Elbowing Fighting High Sticking Holding Hooking Interference Penalty Shot Slashing Spearing Tripping
The standard penalty for delay of game in American Football is 5 yards.
This penalty is called "Clipping".