Well, for Suzie, the last panel of issue 12 is the Vyndktvx arriving in her bedroom while she's asleep. That plus the fact we already knew from issue 6 she was part of his Army....granted we don't know how he turned her to his side (now, she's like 6, that musn't be too difficult).
The back up of 0 is Drekken's origin. At first, it only looks like the story of a young scientist making reasearch on the future Captain Comet, but the last page explains (well, hints so hard that it's explaining) that his experiences to recreate the effects of the meteor that turned Adam Blake into a neo sapiens turn him into this shape shifting thing.
I thought Nimrod's origin was kinda complete. Reason for wanting Superman's demise (the challenge of killing an unkilleable man plus a desire to get revenge after getting scarred in his first fight), a first fight that turned wrong and gives him his look, Vyndktvx telling him that he will giving special weapons......I thought the basics were there.
They are called the Anti Superman Army by the Legion of Superheroes in issue 5 and 6. The rest of the time, Vyndktvx calls them his Army.
Well, you're welcome.