I would argue that it isn't that the Constitution hasn't kept up with the time, but that our government has failed to live up to the Constitution.
When the federal government wishes to grow, it should do so by amendment - there is a process in place for that, and it works.
As for the "services" you mention, the Constitution fully supports the FBI as a federal enforcement agency. As for the standing army, we *technically* don't have one - we have an appropriations bill go through Congress that authorizes the continued expenditure of federal funds to maintain it. If Congress wanted to do away with it, all they would have to do is not pass a bill, and the funding evaporates. While I don't think this was the intent of the Framers, it certainly falls within the bounds of the authority granted to the federal government.
The rest... well, they are unconstitutional. They should be either authorized via amendment, or they should be repealed. I acknowledge that some of these programs are now part of the fabric of the American culture, but that doesn't make them right - it just makes them hard and slow to repeal.
I'm no Paulite. While I think he's got the right idea on domestic and monetary policy, he "bring them home tomorrow" foreign policy is insane. Indeed, he seeks to restore constitutional government - a noble goal - in many arenas, but he seeks to do so overnight. That would be catastrophic for this country.
As for the Second Amendment. I'm sure you're aware that the Supreme Court recently shot down the collectivist interpretation of the Second in Heller. As for the "civic purpose" part - well, yes and no. Yes, individuals were expected to be able to serve as militia to fend off attackers and to keep the peace - but that is not the rationale for the amendment, that is only it's primary use. " ... necessary to the security of a *free* state ... " is the rub - our Framers recognized that a state whose citizens where unable to purchase arms was not a free state.
Finally, as for effectiveness --- having a gun does not make you an effective fighter any more than having a hat makes you a cowboy. It takes motivation, mindset, training, and practice to become proficient in the use of firearms, and to maintain that. I agree that both sides of the argument are guilty of inflating statistics and hyperbolizing (is that a word? It is now!), but in the end, the effectiveness of the weapon is not relevant to it's status as a natural right.