Since she doesn't post that often, I can help you with some of them.  If I've overstepped my bounds, I'm sure the mods will be happy to do their duty.

Re: Mockingbird.  In the original version of the Secret Six, Mockingbird was the one who directed their actions.  Also, it turns out that Mockingbird was one of them.  (He/she kept his/her id a secret because the other 5 were blackmailed into being a part of the Six.)  So Mockingbird is a "mystery character."  Don't know if s/he is supposed to be one of the new Six. 

Re: Doctor Psycho and Scandal - Psycho is a Wonder Woman villain.  Has been since the 40s in fact.  Never heard of Scandal before.  Might be new.

Re: Chesire and Asia.  The impression I got was the Mockingbird's ultimate golas was to take over the world, with the continents being divided up amongst the Six.

Re: Parademon, Ragdoll, Mister Sands, and Multiplex.  Can't help you with the Parademon.  Ragdoll is the latest incarnation of a 40s villain (IIRC, he most recently popped up in the Starman series a few years back - can't remember if it's the original or a protege).  Mister Sands is the Shadow Thief, a Silver Age Hawkman villain currently causing trouble in the Manhunter series.  Multiplex comes from the Firestorm series.  (Don't know if it's supposed to be the original, who had been killed by the Parasite, or a new one.) 

Don't have the montage page handy to help you with the rest.

Hope that helps.

For some reason I assumed the Parademon was just A random Parademon (Darksied's footsoliders -- they were all over Generations III (just to tie this thread to JB by some tenuous means)) who wound up on earth - but i guess we'll see.  Really enjoyed the first issue greatly - it is nice to see someone who can nail the personalities of so many characters from over such a wide span of time.

Okay, got my copy handy now.  On the montage page, we have:

1.1 Gentleman Ghost - Hawkman villain (Golden and Silver Age)
1.2 Don't know.
1.3 Fatality - Kyle Raynor Green Lantern era villain.  Doesn't like all Green Lanterns in general and John Stewart in particular since he accidentally contributed to the demise of her home planet in COSMIC ODYSSEY
1.4 Shrapnel - First appeared in the Kupperburg/Larsen Doom Patrol run and has popped up here and there ever since.  Most recent appearance I know of was in Outsiders #20 (where he died... apparently he got better)
2.1 Knockout - From Karl Kesel's first run on the Superboy series (current DCU version).  Native of Apokalips.  She likes to break things (and people).
2.2 Phobia - From the Wolfman/Perez Titans incarnation of the Brotherhood of Evil.  Currently appearing in Manhunter.
2.3 Don't know.
2.4 Prometheus, from Morrison's run on JLA.  Intended as a "Dark Mirror" version of Batman, in a way.
3.1 Plasmus - Also from the Wolfman/Perez Titans incarnation of the Brotherhood of Evil.  He melts things.
3.2 The Body Doubles - Regular opponents of Resurrection Man, from his short live series. Also got a mini-series of their own.  Callous assassin for hire types.  Mainly appear in "crowd sequences" these days.  Case in point...
3.3 Looks like Gorilla Grodd to me.  I'm sure you know all about him.
3.4 I think it's Satanus (from the Superman titles), but I may be wrong.

Hey, Glenn!

Some of these questions got answered by others, and some are going to stay spoiler-free for a bit, but...

The thing is, it's a book with a huge cast, but most of the cameos are so brief that introducing them fully would really have slowed the book down to a crawl, and would have exaggerated their importance, I felt.  The Six (Catman, Cheshire, et all), and the core group of the Society (Luthor, Black Adam, etc) are the key players.

Mockingbird is indeed a shadowy character in two previous versions of the SECRET SIX title.  Familiarity with that fact is not necessary to this book, but may provide clues for those who are interested.

Scandal is...I'm hushing for now. Dr. Psycho is a long-running Wonder Woman villain.

And quite right, Mockingbird was literally promising them each a part of the world.

And we'll find out lots more about all the leads, not so much about the cameo characters.

And Dave, I think you missed only SKORPIO and SABBAC, if I'm remembering correctly. More to come, too. It's a big bad guy party. ;)

Best,

Gail

Mike the Parademon, an intelligent Rogue Parademon appeared in Total Justice (a miniseries meant to sell the Total Justice line of toys.) His speech patterns were based off of Usenet poster Michael Chary. He made some later cameo appearances here and there. Some people think that the Parademon that appears in Villains United is Mike, while others (like myself) think that it's just a random Parademon, left on Earth during any of the dozen or so times that Darkseid's hordes have struck Earth.

Only Gail, resplendant in her glory, knows.