Few Scenarios i'd like to get clear

All under Federation rules

Play #1

A20 runs the ball on a sweep (they are on their own 40). Approx. 10 yards down field, B35 grabs his face mask briefly for a 5 yard flag (which the official throws), A20 breaks through B35's attempt at making the tackle and fumbles the ball (50 yard line). B35 grabs the loose ball and his tackled (A's 45 yard line). Call?

#2

If you have a 15 yd penalty (say, a block in the back) on B while A is at the B 20 yard line (where the play ends), do you go half the distance or go 15 yards. If you go half the distance, what yardline would A need to be at to go the full 15?

#3

You have a missed field goal by A at B's 15yd line. Does B retain possesion at the previous spot or does the ball get spotted at another spot?

#4

This is more of a gray area. You are working as head linesman. There is a sweep to the other sideline. As you are trailing on the other end of the field, you see a block in the back. Now, the field judge did not have a flag and you see a clear violation. Do you throw the flag? If so, how do you sell the call since you are "out of position" from the play based on that the LJ being there. If not, why should the official let it go?

Thanks guys! I appreciate It!

If your watching his area, then whose watching yours. While you see the block in the back, you may have just missed a major flagrant foul in your area. How do you sell that? "Coach, I didn't see it, I was looking accross the field at a block in the back." Bottom line, when the play is away from you the only fouls you should have are those flagrant fouls and other major personal fouls. Minor rule infractions should be left to those who are in position.

#1 This is covered under 10-3-1d, The end of A's run is where he lost possession (50). The basic enforcement spot is the end of the run. A would put the ball in play from B's 45.

2# First, a block in the back is 10 yards. But the answer is the 30.

3# Missed feild goals are scrimmage kicks. If the kick ends in the field of play, the succeeding spot is the end of the play. If the kick goes into the end zone, it is a touchback. (NF) NCAA is previous spot I believe.

4# First of all, if you are seeing blocks in the back in the opposite side zone, you are watching the wrong area. This is the hardest thing a young official (some vets also) has to learn, looking away from the ball carrier. When the ball carrier is entering the opposite side zone, you should turn your attention to the area behind the U & BJ (five man). And yes you are correct, even if you see it it is a hard call to sell.

Penalize from the end of the associated run. 5 yards from the 50 to B45 yard line if A accepts the penalty.
All yardage mark-offs can't move the ball more than half the distance to the goal line. For a 15 yard penalty to be fully marked off the foul must occur at the 30 or further out.
A field goal kick is what we call a scrimmage kick. This is the same thing rules wise as a punt except it can score. If the ball breaks the plane of the goal and doesn't score it is a touchback. If it stays in the field-of-play then it can be returned or downed just like a punt.