My current understanding, is that now that I’m exalted with both Zandalari and Honorbound, if I faction change, I will be exalted with their opposing factions, and all I have to do in order to unlock Dark Iron Dwarves and Kul’tirans is to do the war campain and corresponding unlock sequences.
Is that even close to correct? The way that Zandalari required the quest “The Final Seal” would I already have that completed on Alliance side? Or would I have to basically do every single quest in each zone before hand?
The reputations will convert to their Alliance equivalents, but the quests will not. Completing the war campaign on one faction will not unlock it on the other, but IIRC, if you have the Zandalari rep exalted (and, subsequently, Proudmoore Admiralty after changing), you should be able to breeze through them.
You will need to do the zone quest achievements on your faction changed toon, I think.
Yep, your Horde reputations will covert to the Alliance version. Once you complete the other requirements you’ll be able to pick up a quest in the Stormwind Embassy that will lead to the Dark Iron Dwarfs to join up and be available at character creation.