Is muscular strength specific

Answer 1

Yes ... VERY!

A person can have powerful quads, but only have average arms or wrists.

Have you ever noticed the Huge difference in muscularity between Roger Federer's right forearm and his left: he builds his right for holding the racquet and being able to impart great spin on the ball, but he only needs his left arm to toss a ball in the air for service.

I have seen many sportsmen who have mainly 'running' legs [as in strength and musculature, but powerful shoulders and arms that they put into use in body contact situations: others have thick legs and thighs that they use to 'plow' their ways through packs - often leaving a number of other men lying on the ground as a result.

Strength and fitness are also specific:

For instance, a person who plays tennis regularly may well have a try at playing squash and walk away sore the next day ... and so on.

Every particular skill needs its own training regime.