First of all, this is great stuff. It's got a very Earthsea vibe, and I love how you're working in dragon psychology into the actions of the dragons, but still keeping the "dominance" in line with their alignments. That part reminds me of Thri-kreen of Athas, where their clutch and hunt instincts influences everything from party dynamics to how they buy goods in the market.

Some of this does not necessarily NEED to be revealed; while you might want them to know that he's a dracolich, if you're planning a "boss fight" (though "he's a dracolich" can be a reveal in a 1st boss fight, leading to a quest for the Phylactery, leading to a 2nd boss fight), a lot of this can just be chalked up to "He's gone crazy and is demanding more things that are evil". You need to know it, but they don't need to know the particulars of dragon psychology unless they want to.

Where do you picture them being in this conflict? Are they agents of Ziirka? Are they aligned with Kyros? Are they somewhere in the middle? If the latter, are they likely to become uncomfortable with his demands? If the former, might they resent being pawns? Similarly, though, you need to think about what Ziirka will know, when she's going to learn it, and how she'll react... I imagine finding out her old frenemy is a dracolich will shake her a bit, and change her tactics.

Myself, I start by plotting out what will happen if the PCs don't get involved. If your players decide to **** off to Undermountain, or play Cash and Caravans instead of adventuring, what's going to happen in the world around them? What are Kyros's moves, what are Ziirka's countermoves, and when does Ziirka change tactics, having learned the truth about Kyros, or at least deciding that he's gone from "make the world better" to "evil warlord"? Have that rough map, then let your players rewrite it. Know your lore, but keep it from the players unless they seek it out, or you need them to know it.