Yep, given the reality of how many firearms there are already, and the resources it would take to remove them... I think we should focus on other things.
Who says the government needs to remove them? There could be a grace period of a year or maybe several years, during which people already owning a gun can apply for a license and receive the necessary training. Those who don't want to get the license can come in to prove they made the firearm unusable. Anyone else owing a gun can be made liable after that grace period. This would minimize necessary resources.
Also, a proper government should be able to focus on several things. And I do think daily school shootings is something worth focusing on.
I agree that this is worth focusing on. Your suggestions would help. Sadly that doesn't remove the firearms already in the US. Meaning that criminals can obtain them.