Do things like bloodletting and staunch etc complement Villager Defender skills or are they redundant?

Sort of both.

Redundant in that, hey, you have two answers for, say, plague (three if you count herbs) and most people only have one.

Complementary in that all these abilities have reuse timers, and sometimes their mechanics are directly complementary. For example, bloodletting would make a plague significantly weaker if successful, which would give poultice a better chance of curing it.