All the details I'm missing or are unsure about will be gathered here; if you can help me with anything, mail me at jigsawmen [AT] googlemail [DOT] com or leave a comment over at my blog, Crisis On Earth Prime.
Page 17 - Panel 1 The villains' confrontation with the Justice League. From left to right are: Red Arrow in the foreground; Poison Ivy; Cheetah; Killer Moth; Black Lightning; an unknown pink/purple skinned woman kneeling behind him in a blue leotard - if her skin were pale I'd be tempted to say Killer Frost; Captain Cold; Hawkgirl; Red Tornado; Signalman; Black Canary; and Vixen.
In the large gathering of heroes on Page 18 (shown on the left) the character in the top left, number 1, is Unknown.
Pages 12-13 - Panel 1 In the skies above Checkmate's castle, Hawkgirl battles Silver Swan though I'm unsure as to who the flaming, flying character on the left is. Anyone?
Page 24 - Panel 2 Above the Checkmate castle from the top down are Killer Moth; an unknown Justifier; Hawkgirl; possibly Sun Girl; Green Lantern Alan Scott; Bolt; Man-Bat; and, in the whirlpool, Typhoon.
Page 13 - Panel 2 From the top down are Starman; what could be Gorilla Grodd or Titano; Frankenstein; probably the Question; Red Devil; Power Girl; an unknown with a green top in front of the OMAC robots; Supergirl again; Iman; and Wonder Woman.
Page 18 - Panel 4 Between Superman and Darkseid are Mirror Master and behind him the Human Flame; over Darkseid's shoulder is Captain Cold; behind him is an unknown woman - any guesses?
Page 30 - Panel 2 After the fighting, life gets back to normal. In the offices of the Daily Planet, Perry White (on the right) holds a meeting with his staff. Left to right are Ron Troupe; an unknown with his back to us; another unknown facing us; Clark (Superman) Kent; Lois Lane; and Jimmy Olsen.