OK, so your low side switch is a worry for a start - particularly as you will be reverse-biasing both of the upper transistor junctions when the lower is turned off - that certainly can be a problem, though you could include a signal diode in series with the base.
Having whole sub-assemblies floating "high" when turned off is in general, a bad idea. All sorts of things can happen!
This looks better. I don't see any point in a Zener. Will a servo run at 3.3 V logic? I would first see how well it runs when you turn the voltage down to 3.0 V or 2.8. Test it first.
Oh yes. With no signal, most common servos will simply lose hold - they will resist movement to some mechanical degree but generally can be forcibly turned.