The correct answer for the first measurement is:
Measurements start at the front leading edge of the rubber and continue to the back point of the plate.
The correct answer for the second marking is:
The angle formed by the back end of the plate is the baseline for 1st and 3rd base respectively, AND CONTINUES ALL THE WAY TO THE FOUL POLE(S) ON EITHER SIDE IN THE OUTFIELD..
I know some of these questions may seem unrelated to the pitcher's position but their not. Any player who plans on making this sport a serious part of his/her experiences, should know as much as they can about the environment they compete in. Your knowledge of this sport can, when coaches are determining who's who to pick between two or more players that are very closely matched playing wise, be that little edge - that's just enough to beat the other guy(s) out of a job on a club.