I think freedom is the first priority. We can't trade freedom for security.
I also have some concern about immature persons creating a security risk. I don't think concealed carry adds significantly to this risk. But I do have a concern about the accessibility of any firearms for immature persons. An arbitrary age limit is a poor qualifier. Because we have the same arbitrary age limit for voting, military service, and the adult criminal justice system, it would be hypocritical to legislatively deny firearms, prostitution, gambling, alcohol, and tobacco with a different age limit.
There does not seem to be a practical qualifier that has a reasonable chance of being substituted for the arbitrary age limits that are in place. People only seem to be debating shifting them up and down.
Education and training seem to be conducive to producing the maturity and skill we'd like to see, but they should not be a barrier to rights and liberty. Rather than mandatory classes as prerequisites to government permission, I would prefer to see a proliferation of highly-accessible education and training in firearms. While I believe parents have the primary responsibility and role for this training, I'm not confident that many, even most of them are properly equipped for it. High-accessible training could be on-campus training at high schools (before, during, or after hours). It could be at public ranges. It could be through 4H -- but their current programs of rimfire rifle and shotgun aren't enough. There needs to be training in centerfire pistol and AR-style carbine.
No one should be turning 18 in this country without at minimum the kind of training that comprises a full day CCW class, full day Hunter Safety Training class, and with significant range time with a pistol and carbine and an instructor. Again, I'm not saying it should be mandatory, but highly-accessible. Highly-accessible could be "free" or paid for by Pittman-Robertson type funds -- in other words, they'd pay for it with their purchase. It could also be charged on the principle of ability to pay. In other words, pay for it if you can, if you can't or won't then we'll find some generous donors that need a place for their money other than Lapierre and Ackerman McQueen's pockets.