I carry my -75b in C1, safety on. The trigger reach with the hammer back is quite acceptable.
The correct way to hit the slide stop (this is true for any pistol, not just the CZ) is to use the thumb of your weak hand. Drop your empty magazine, seat the fresh mag with the heel of your weak hand, and bingo! Your weak thumb is right there. Give it a try, see how it works.
The way to decock the CZ-75b is to manually lower the hammer with your weak hand while pulling the trigger. It is perfectly safe if you are careful. Make triple-sure that you are pointing the gun in a safe direction. If you carry the -75b cocked and locked, you should rarely or never need to manually decock it.
- Chris