1) If guns were completely banned gun use would drop across the board. Gun crimes would drop. Gun deaths would drop. Guns confiscated at the scene of a crime would drop. There would still be some guns around. Many currently law abiding gun owners would simply stash their guns but have access to them, if not immediate access. Criminals would still occasionally (maybe even somewhat often) use guns in the commission of a crime. Occasionally a person who otherwise would have had a gun will be victimized, maybe raped, maybe killed, maybe beaten or maybe just violated in some other way, because they gave up their guns when they became illegal.
2) This would be far less effective. It would also be extremely unfair. I've stated several times that gun rights are linked directly to the concept of individual rights. That individuals own their own existence and as such they have the right to defend their existence. Connected to a person's right to defend their existence is the right to posses the tools that make that defense possible, i.e. guns. And not just granpa's old hunting rifle, guns that are of a capability to be useful in any foreseeable threatening situation, including the threat of a tyrannical government. To single certain segments of the population out and deny them that basic right is not consistent with the notion of universal individual rights, which is what I support.
What's disgusting to me about the way Sandy Hook is being used is that it is dishonest. I suppose some people might rationalize it and say "whatever we can do to get rid of as many guns as possible is good and therefore sufficient justification to lie and to take freedoms people currently posses away." But I fundamentally disagree with the notion that the ends justify the means. I believe principals come first and even when certain aspects of the outcome of implementing those principals is bad it is only acceptable to change the way things are done if it is possible to identify the flaw in the basic principles used. I don't believe in the notion of a perfect society. I believe attempts to create a Utopian reality have caused some of the greatest horrors known to man.