Both the Federalist papers, the militia acts, and current government code confirm that everyone not part of the standing military or national guard as the militia. The militia doesn’t get free guns, they were expected to bring their own privately owned guns and ammunition when called upon. I would not mind free guns though.
Training should be part of the public education system, but gun/hunters safety and shooting sports have been removed because it’s not kosher to expose kids/teens to guns. Due to the prevalence of guns in the US it just makes sense, because treating guns like abstinence only sex ed will have the same shitty results.
The “buy it at Walmart and figure it out” is because you can’t lock rights behind hoops to jump through, so adopting a Swiss model and making fun education/training part of compulsory education is definitely a good minimum.