If wire in series like I described the crossover ('filter') "should" only affect the tweeter as theory goes that power flows from positive to negative. According to theory the power should flow through the woofer before going through the tweeter. Speakers operated on pulsating DC current so power only flows one direction.

Theory says anyway.....

As far as impedance values, I am only throwing out a guess, but generally amplifiers can handle more resistance than spec better than less resistance than spec (ie. 8ohm rated amp will run 16ohms fine versus having problems running 4ohms). This is only a general guidline and varies based on specific amp circuits.