User blog comment:Ducksoup/Sprucing up your Main Page: Introducing the Hero Image/@comment-1038387-20150227191418/@comment-24739709-20150227193800

1: the cover images will be inserted into places where the old "Promote" images were used.

2: that mockup is ever-so-slightly dated. We removed that "Edit" text because the pencil icon seemed self-explanatory.

3: yes. I believe there is an extreme edge case where an anonymous user may see the zero-state, but that's being fixed now.

4: there are no ratio requirements, though obviously some will look better and/or fit better. And yep, you can vertically center any image.