Druid is the best fit for a Zanda, IMO.
As for the rest:
Great choice, I did the same.
I think regular Tauren are better Warriors, but this is not a bad idea.
I get it, but again, there are better Hunters. Give Shaman a try for Highmountain. I felt like mine was a good fit.
Interesting choices. Again, I get it, but I still think Druid fits them best.
I had a tough time with Vulpera, TBH. Strictly talking DPS, they are the worst race in almost every available spec. As for “theme”, Shaman is kinda interesting, as is Hunter. Rogue is iffy, IMO, though Outlaw kinda feels right for them. I went Hunter with mine and I don’t regret that decision. I feel like the “camp” ability makes it make sense to be a Hunter.
Zero disagreement here. Mage fits perfectly for them, I made mine Arcane for the theme. I feel like the three casters are their best options (though I might entertain a Hunter eventually just for giggles).
Void Elf: Monk (Source: Trust me, bro) (alternatively, you could go Warlock)
Mecha: Warrior or DK (Hunters are fun as well, but I’m told mechanical pets suck for Hunters in general so if you were looking for a “theme” there are better Hunter options)
Dark Iron: Shaman, Warrior or DK (All three benefit from the racials in some way and thematically all fit pretty well).