4. No, I call for everyone between 18-46. We simply delete the male stuff.
Of course ownership and the right to bare is an individual right so it is not conditioned on participation in the militia. You would have the right after your service period or if you were unable to reasonably serve due to a handicap or something too.
I think that there should be no standing Army (boots on the ground, armor, etc). Due to skill level requirements and modern realities we would maintain a standing Navy and Air Force. The Army would be replaced mostly with the militia. Folks would serve and train for a year in a stretch and then a few days a year to maintain proficiency unless called up for a national emergency. Special forces and a small contingent of Marines (say a division) would continue to exist, along with brass. The militia could only serve in the US.
I'd close 90% or so of all bases worldwide but would add several carrier groups to maintain our ability to project power globally.
Conscientious objectors would be fine, they would serve in support roles but be excused from combat related situations and training.