Quote Originally Posted by Throbert McGee View Post
Question: Could всё на х*й or всё на фиг be used with the same meaning as всё зря?
No, the first two phrases most probably should be translated as "To hell everything!" (depending on context)

P.S. As long as I'm on the subject, what is the exact difference between моряк and матрос? Can they both be used when talking about "the Navy" in military contexts?
Yes. Basically, моряк is everyone who sails while матрос is a subordinate employee (or serviceman) on a ship (both civil and military) who most probably wears a uniform. Captain of the ship is not матрос but моряк as well as field officers.