Design 20 looks more safe on this matter, compare to other options, Two additional low power transistors do great work, to ensure there is no through current. At least at low freq. PWM
Yes, as long as you don't muck up in one of the ways I mentioned. Eg, how many
people have accidentally shorted 2 pins with a scope probe, or dropped a screw
driver on the circuit board. Answer: everyone. The nice thing about integrated
h-bridges is they have a lot of protection built-in. Over-temperature, over-current,
inability to scope internal nodes, etc.
Still, probably best to use a fuse in the power line. Any kind of short will likely
pour in so much current the fuse will pop quickly.