As for the questions:
DC has Wildstorm (Apart of their Multiverse) and Vertigo stories to draw upon. On top of their classic runs like Johns Flash, JSA, etc... Waid's Flash and Kingdom Come, Morrison's JLA, Batman, and Superman. Etc... Both mainstream companies are neck and neck, but what REALLY puts DC over the top is Vertigo.
Both have great characters. Marvel has the best villain, IMO, which is Magneto, but DC has so many obscure gems on top of their mainstream heroes like Batman and Superman that they take the cake.
DC is simply overpowered. Whether you are talking Pre-Crisis or Pre-Flashpoint. Even the editors at Marvel have said that DC is GENERALLY more powerful. DCnU is another story. DCnU is still considered a baby and because of that, Marvel is more powerful currently, but DC in general.