Do you think requiring someone to get training prior to purchase is a bad idea?
I think training is a good idea as well. But i don't think that requiring training is wise, unless it is publicly funded and part of our national education system. Just like being knowledgeable of national policies and history is a good idea before one votes, i wouldn't suggest we require everyone to pass a test to vote.
How did you get a driver's license?
Driving isn't a right, FWIW.
Driving itself is a right, if one owns the vehicle and the fuel. It's driving on publically-funded roads that's regulated, not the act itself. This is not a practical distinction for most people (is for me, with a private road on our property, which is why I thought of it- we were free to run our rock hauling truck up and down the mountain without keeps tags on it since we didn't take it on public roads).
But I do think the distinction gets to the heart of the sorts of constitutional questions we're batting around here. The argument is that the public has an interest in being sure those who drive on the public's roads are doing so safely. As population has increased, land parcels have shrunk, and pavement has spread everywhere, we've reached a point where it's not possible to accomplish daily life without traversing public roads one way or another, so the regulation has become restrictive in a way that might have changed its fundamental nature. But the original distinction was (is) meant to draw a line between the public and the private.
Rights do not have to be spelled out in the constitution to be rights - that's sort of the whole point. It's why Ben Franklin (I think it was) originally opposed the Bill of Rights - he was afraid people would come to think that the rights spelled out there were the only ones, instead of everything not explicitly restricted and not infringing on other citizens' rights being an inherent right of a citizen.
With guns, we actually get into more complexity, since it is spelled out in that Bill of Rights Franklin (or whoever it was) opposed, but now there are regulations in place anyway, some of which our Court has upheld. It's left us with no real clarity on the issue at all, which is probably a big part of why it's so contentious.