On-sale date from copyright registration.
Art credits for this cover were a matter of some debate on the GCD-Main email list. Agreement is that everything except the Superman/Batman and Robin characters are by Swan/Kaye. There is some doubt about the Superman/Batman and Robin characters as possibly being by Win Mortimer. Win Mortimer denies having any part of this cover in a conversation with Craig Delich, so if those are Win Mortimer figures they were most likely added by paste-ups from the production department and not drawn by Win Mortimer specifically for this cover.
Letters credit from Todd Klein via his Klein Letters blog (18 September 2016, http://kleinletters.com/Blog/ira-schnapp-in-worlds-finest-comics-part-1/).
inside front cover
Showcase Presents: World's Finest (DC, 2007 series) #1 lists Stan Kaye inks. Klein/Reed and Archives incorrectly list Paris inks.
Wayne Boring Superman image incorporated into this puzzle page.
Green Arrow wears red hat.