What is low blood pressure for a male?

It's arbitrary: Normal blood pressure is defined as 100-129 systolic, for both males and females. But some people have lower blood pressures and still have adequate perfusion of organs, without any symptoms of dizziness, and hence it is "normal" for them. If somebody has baseline BP of 85-90 and tolerates this fine, it may not be pathologic. That said, this is far more common to see in females than males.

Depends : It depends on age and size. BP ought be >80/50 and more commonly is >100/60. Normal is up to 135/85.