That is incorrect. The National Guard are part of the US Army.The National Guard is not a standing army.
It doesn't have to mention it. Collective defense includes repelling foreign invasions. That means firepower appropriate for repelling foreign invasions.The Second Amendment needs to be seen from the right angle. As I said, it prevents the US federal government from stopping individuals being able to own "arms". It doesn't really mention what types of arms.
I'm not wrong. What people had back then was modern infantry weaponry. Hunting was decidedly not part of the right to keep and bear arms.The reality is the militia was designed to have people with their own weaponry that would be every day weaponry for hunting, what normal people would have. Not cannon or other such weaponry used in high tech warfare of the day. So, from both points there I think you're wrong.
If you want to exclude weapons that are too large and expensive to be owned and operated by common individuals, that is one thing, but limiting the right so that it covers only "individual" infantry weapons still leaves full-auto assault rifles and things like grenades and bazookas.
If they had had the Second Amendment, they would not have to get the weapons from somewhere. They would have the right to provide their own weapons.Collective defense means people getting together to defend themselves. Take a look at the Ukraine. People did not have all the weaponry they needed, but they still got it from somewhere.