Israel has the right and most effective approach. They had a massive school shooting nearly 50 years ago, they live in a war zone. They put armed guards at schools, like really armed, not just a beat cop with a sidearm, we are talking like European airport security armed guards. They armored schools with strong doors, restricted access and so on. They then offered training to staff who volunteered in order so that they could be armed, trained and equipped to defend kids in the case of attack. They haven't had a school shooting since. End "Gun Free Zones"
The rest of the crap you outlined is a suicide pact of restrictions rife with abuse that will get even more people killed and has already with red flag laws and so on. Acquiescence, laws and disarmament doesn't and hasn't worked even in countries where it's basically impossible to own a gun. Vigilance, responsibility and emotional strength in the never ending battle against evil has proven the only effective means of prevention/deterrence. To say otherwise is to ignore the facts yet here we are again with people arguing that some law will make up for their lack of moral courage and emotional maturity.
The only thing that stops a bad guy from committing violence is a good guy willing to commit violence on behalf of the innocent and if needs be lay down his life in the defense of others. Nothing else has ever protected people and society effectively and it's time we as a society re-learn that.