I like your ideas. I think they more reflect how strategic bombers worked. One thing that always bothered me is someone sending transports for an amphibious assault escorted by bombers to fight any scramble planes. For the game it does make sense, bombers attack @4 so they would be great to deal with scrambling fighters and/or tacs. However, in reality, it is just ludicrous.
Also, I think the idea of defending bombers having a defense of 0 is a great idea, as well as your “chosen last as casualties” idea.
I agree on what you found ludicrous.
I provided a way of turning things a bit differently not only for Strategic Bombers but mainly for Tactical Bombers,
in this more defined HR on aircrafts units:
Rethinking Air units simulating historical air-to-air combat
Hope, you can like it.