Tom,
#1 Shooting into the air is not a firearm issue. It is reckless endangerment of human life and property. Reckless endangerment is illegal, so why do we need special firearms laws that can be interpreted to specify something with arms? The actual act of falsely shouting fire in a crowded venue is not illegal, but the reckless endangerment it causes is. The reason we know so much about this particular phrase is that the Supreme Court of the United States has ruled that my free speech protections end when I endanger someone else's basic rights.
Over the years we have become conditioned to believe that we need everything very specific and black and white. The Founding Fathers did not craft our Constitution in this manor, because they wanted to protect us from the stupid concept that it was only as things were the day the document was signed. That is why #2 we can correctly say that modern arms are protected, as opposed to only flint lock firearms are protected.
We are in complete agreement on number 1, on number 2 another thing to consider is that when we today consider the "arms" mentioned in the 2A we think only of pistols, rifles, and shot guns.
That is NOT what the Founders intended or said.
The 2nd A DOES NOT PROTECT "GUN RIGHTS".
The 2A specificlly states "ARMS" NOT "GUNS".
"Arms", as used includes all weapons from slings to ICBM's.
The original intent was every thing from bayonets to the latest naval cannon which were quite often placed on privately owned merchant ships.
The possession of plutonium is highly restricted so nukes lack the critical component, but as written the 2A protects everything else .
The Supreme Court affirmed this interpretation in the Miller decision by finding that Miller's sawed off shotgun had no "military utility".