1. I agree with what you wrote here. The conversationI had with a guy who was at the protest, we both agreed that letting crazy people have guns was a bad thing - but the point he missed was that Cho passed the background check. Just how helpful is it in that situation? It's not, because the "background check" probably doesn't hit the right spots - but I'll just leave it at that. So if it fails in a "Cho like situation" where a background check is run, what's the push to do it in private sales? In that last sentence is the real problem. In either case, it's not likely to catch a crazy person, and unfortunately we have proof.
2. Gun buy back, aside from the silly name, the catch-22 with this program is that you potentially let criminals slip through the cracks either way you go. I guess what's the greater good for society as a whole comes into play here, but that's iffy at best. Do you let a (hypothetical situation being described) serial killer dispose of his guns across the US at these programs, so they are never traced back to him; or do you register everyone who turns one in to get their cash, and reduce the turn out and getting guns used by people who shouldn't have them off the street? That is a tough nut to crack there.