"2nd only provides for the National Guard to possess firearms".
That is subject to some significant debate. Further, the Supreme Court deemed it a private right to ownership. The NG isn't really a militia, it is a standing army of the State. Also, at the time the term 'well regulated' meant working, properly configured, or well designed. It did not mean subject to a high degree of government regulation. Also, a militia often meant all free males between 6 & 60 in the county or town. Personal arms were indeed kept in the home to allow for quick mustering and prevent there being seized by an invader. Some jurisdictions required eligible persons to purchase a weapon & ammunition.