I say that is a completely different topic and I'm not sure why you brought it up other than to try to be a smart-ass. What you mentioned is not undermining the constitution, and as such, is completely off-topic.
Yes, it is. Any misinterpretation of the constitution is an undermining of its intent and effect, regardless of whether that results in a situation you like or not, and the pure individual right interpretation of the Second Amendment undermines states' rights.
A militia was a force of the proletariat. Every man that was able to take up arms was expected to do so. Therefor, the common man was considered militia and did *not* need to join the army nor any other organization to be considered such.
Yes, it was made up of the people, but the whole phrase "well-regulated" is not mere puffery. It means a militia in proper and working order, and it explicitly referenced as "being necessary to the security of a free State." The governments of the states have long been held to have the right to regulate arms within that context, and the federal government has the right to regulate firearms that do not have a purpose in a militia. (See US v. Miller (1939) on regulation of sawed-off shotguns.)
Anything not specifically outlawed by the constitution or the state is defaulted to being a right. Therefor, yes, you would have the right to own a gun even if the 2nd amendment didn't exist.
Unless a state passed a law saying that you didn't, by your own statement.