This is the best answer, and I don't think it's rude to just be short sweet and clear. Use the Amp, the HU power is not wasted, it's allowing your signal to the amp to be that much cleaner. 85W X 4 is plenty, no reason or need to bridge.to answer your questionsno
no
no
no
no
You would actually be wasting MORE power if you bridged the amp and used your HU's speaker channels, since you would not ever come close to using the 200 Watts in daily normal use and you would have to both overdrive the HU powered speakers to be audible or attenuate the hell out of the bridge amp channel.
It just wouldn't be efficient or good sounding. It would be to use your words, wasted power.