Jingo/WMG

WMGs for Discworld/Jingo. Warning: Potential unmarked spoilers.

The alternate Vimes from "Jingo" became a zombie
If anyone on the Disc has an iron will, It's Vimes. And, in that fight, he had everything to fight for. Revenge, home, justice, honor etc. When a man who won't quit and has a good reason to stay on earth dies, zombies tend to pop up. I'd say alternate Klatch would be in for a surprise.
 * Never mind alternate Vimes. There's plenty of fans out there that think that when Vimes dies he probably won't stay dead. After all, zombies on the Disc are the result of sheer stubbornness and Vimes is bloody-mindedness incarnate.
 * Besides, given his normal opinion of undead, it would be just too amusingly ironic.
 * Actually he has no problem with zombies and werewolves. He's quoted as calling Reg Shoe and Angua (separately) "his best officers". It's just vampires.
 * You seem to have misunderstood. Vimes doesn't like any of the Disc's races. The important thing is, once you're a Watchman, you're a Watchman, and at that point it doesn't matter what race you are. Detritus said it best toward the end of The Fifth Elephant, after shaking hands with the Low King. He remarks that he's never shaken hands with a dwarf before, and Cheery mentions he's shaken hands with her. Detritus responds, "You're not a dwarf, you're a watchman."
 * Vimes himself admits to liking gargoyles. They never commit any crimes anyone finds out about.
 * Er, Fridge Horror ring a bell? The OP must really hate Vimes, if they want him to have to (un)live on as a zombie, burdened with the knowledge that nearly the entire City Watch had gotten slaughtered because he didn't choose to leave the city. And he'd know they'd have lived if he had, because the Disorganizer would've given him regular updates on his counterpart's victory.
 * Not to mention how it'd continually rub zombie-Vimes' nose in everything else he had to miss out on, from his counterpart's life. "Six PM Monday: Read to Young Sam. Six PM Tuesday: Read to Young Sam. Six PM Wednesday: Read to Young Sam..."
 * Well, I doubt he'd actually keep the Dis-organizer, he'd probably chuck it. But it'd still be depressing.

the events of Jingo were a contest between Fate and the Lady
Similar to the situation in Interesting Times. Fate takes the stronger position, the Klatchian Empire, while the Lady uses Vimes and the Patrician to stop the war. Him getting the wrong Dis-organizer and the freak weather conditions are a side effect of her influence. Klatch was gearing up for war against them already, so the Lady created the Leshp situation to provide a method by which the war could be defused.
 * Aren't all major events on the Disc a result of the gods' games? I thought one of the books kinda implied something like that.
 * Mostly it's just the ones involving Rincewind. The gods aren't that imaginative a bunch, so they stick to the old favourites.
 * The war in Small Gods was a game between two country's deities.
 * While the gods play these games all the time, The Lady isn't always present. And when she gets involved strange things tend to happen.

Alternate!Vimes somehow ended up following the Dis-organizer and saving everyone.

 * It might be out of character, but wouldn't that other Dis-organizer be telling that Vimes the other Vimes' triumphs? Perhaps that would lead to him following it in some form.
 * The alternate Dis-organizer would be telling Alternate!Vimes about what's happening in our Vimes' universe, but he and the rest of the watchmen DID die in the alternate universe, as heard from our Dis-organizer.
 * Technically, it tells him what he is scheduled to do - the whole 'looking at the wrong leg' thing began when Vimes wanted it to, essentially, tell the future. Thing is... you don't necessarily need to follow your schedule.