I’m a red and I got this:
It feels like dialog for Man’ari only, because he says I’m doing good work on behalf of the Man’ari penitents, which kinda implies I’m one of them, so I’m curious if boring Draenei get different lines.
No that’s only for those who are using the Manari skin. It’s really cool! There’s also different dialog for dks! They really went all out with this questline and I love it!
What’s it like? I want to know all the dialogs 
Nope, it’s unique for Man’ari skins, as someone else said, when you’re at the Auchindoun part, Death Knights get dialogue about how you’re already familiar with death.
Those are always nice touches.
If a man’ari and a draenei have a baby, is it a purple half-demon?
Manari are warped eredar. Assuming they can breed their kids should be normal looking Draenei.
It’s the same as lightforged. When they have kids the kids are regular Draenei that make take up the path of lightforging if they wish.
your a red floo- i mean a red lava rock.