The clutch safety switch only requires you to push the pedal down. In case of a clutch faliure, the car will still start in neutral.

The piston in the master cylinder is spring loaded... it will always pop back out if you push it in unless the sping is snapped (extremely rare.)

It's too late to function check it since you already ripped it apart.

It is wise to replace the master and slave cylinders at the same time. Replacing only the master often causes the old slave to blow.