It is a "Libero" which is a main defense player.
There is no limit to the amount of defensive specialists a team can have.
Doesn't matter, as long as you have more 3.
Yes
A defensive end is the name of a defensive position in American and Canadian football, situated at each end of the defensive line.
Defensive driving are safe driving techniques that drivers do to avoid another drivers mistake.
Sparta
guild
From my experiences a defensive specialist is usually called a Labero. (La-bear-o)
The back 4
some long-name thing
A loophole is another term used to refer to an arrow slit in a defensive structure or fortification.
This is called a Crime Laboratory Analyst.