Safety switch vs arming


I do understand that having both safety switch and arming procedure combined is a nice safety feature.
How are these two different from each other?
I know before pressing the safety switch Cube is wont send any signal to ESC. With switch disabled would Cube send signal to ESC just after i plug the battery or wait until i arm it with RC sticks?

Would it be a bad idea to disable the safety switch and only use arming(rudder/th stick) before flight?
What are the parameters for disabling it?

Also, is it possible to enable and use a second safety switch instead the one on top of Here+ GPS puck?