Ernst Udet bailed out of his Fokker DVII when his radiator was shot out some time in 1918...
Some Germans were given parachutes, while others weren't... and by this time it was late in the war that the German pilots recieved parachutes.
BTW, the gun development did not go from rear observers to shooting through your own prop and getting it shot off.. instead it went to a gun mounted on the fuselage of a 1914 Recce RFC recce machine that fired down and to the right. Shortly after that, the first fighters were born (Morane Parasols and Morane Saulniers) that used deflector gear... which was just a solid triangle mounted on the prop, so any round that would strike the prop ricochetted off it. Then later came the synchronization gear which stopped the gun from firing anytime a propellor blade was in the way by use of a simple pushrod system.
-SW