Sorry so late on this. There's actually not a lot to annotate this issue, despite the amount of on-panel chaos, and the Legion blog has already gotten to a lot of it... so let's get to the rest:
Tyr, created by Cary Bates and Dave Cockrum, first appeared in SUPERBOY #197. Neutrax, created by Gerry Conway and Joe Staton, first appeared in SUPERBOY AND THE LEGION OF SUPER-HEROES #253. Ol-Vir, created by Paul Levitz and Keith Giffen, first appeared in LEGION OF SUPER-HEROES #294.
Yeah, Karate Kids don't have much luck. Tusker, created by Jerry Siegel and Jim Mooney, first appeared in ADVENTURE COMICS #331.
Valor is an alternate version of Mon-El whose backstory makes my sinuses flare up. Andromeda, here, is the L(II) variation on L(I)'s Laurel Gand--created by Mark Waid, Tom McCraw and Lee Moder, she first appeared in LEGION OF SUPER-HEROES #66 in 1995, but the original Laurel was created by Tom and Mary Bierbaum, Keith Giffen and Al Gordon, and first appeared five years earlier in LEGION OF SUPER-HEROES #5.
Andromeda hasn't seen Kal-El on panel before; this has to be a reference to Johns' "untold first meeting of the three Legions" thing.
Apparition is the L(II) version of Phantom Girl.
Luthor lived in Smallville (and started losing his hair in his teenage years) per ADVENTURE COMICS #271, as well as SUPERMAN: BIRTHRIGHT.
Luthor's father is Lionel Luthor on the Smallville TV series; was he ever given a name in pre-Smallville comics? Anyway, showing him from the back and leaving him unnamed here gets around the problem.
Which sister? Not Lena Thorul? Or is it? I imagine we'll be seeing more of this stuff in Johns' forthcoming history-of-Superman mini.
Only one brain in a jar!
The Legion Omnicom has a pretty comprehensive rundown of what's in the trophy room, so I won't repeat it here.
Earth-247 out of... 52? We saw it before in INFINITE CRISIS #6.
"The keystone to the multiverse"? Earth-0, then? The Flash connection to Keystone City is appropriate, I suppose.
Okay, this is all fairly baffling, so let's try to debaffle:
Don and Dawn Allen, the original Tornado Twins, were created by Jim Shooter and Win Mortimer, and first appeared in ADVENTURE COMICS #373. (...In a story that's now out-of-continuity post-Crisis, but does have a fine Neal Adams cover.) Don Allen and Meloni Thawne are the parents of Bart Allen, a.k.a. Impulse/Flash IV/Kid Flash. (Meloni and Digger Harkness are also the parents of Owen Mercer, the new Captain Boomerang.) Dawn Allen and Jeven Ognats are the parents of Jenni Ognats, a.k.a. XS.
The whole business with Professor Zoom, his "25th century speed soldiers," Starman's uniform as a map to the multiverse, etc.--the first Lo3W story--is all being mentioned for the first time here.
Tharok, created by Jim Shooter and Curt Swan, first appeared in ADVENTURE COMICS #352.
Bart Allen/Kid Flash here, created by Mark Waid and Mike Wieringo, first appeared in 1994's FLASH #91.
And that's it until the last two issues come out, which I gather is going to be a while--#4 is currently scheduled for Mar. 25 and #5 for May 13, but I wouldn't be surprised to see them later than that...
Also, in reply to a couple of queries, I don't think I'm going to be dealing with the FINAL CRISIS AFTERMATH books here. But I look forward to seeing what other people have to say about them.