They're looking to expand the currency tab, but a recent wow powerleveling post from Wryxian on the EU forums makes it pretty clear that the devs won't be adding 'legacy' items to that tab. There might be exceptions to that like the Darkmoon Faire tickets that are still relevent in Wrath, but for the most part any additions will be from current content, not past content. Sorry, but you're stuck with your research tokens!

Yes and no. As far as we know, Trolls had no divine ties in their creation. They just evolved, and came to exist over time. Their story could use more fleshing out, but it's kind of established that they're wow powerleveling their own thing, no gods or Titans created them. That could change, of course. The Tauren have a creation myth which is most likely just a story, but this is a pulp fantasy setting, so it very well could be true to some extent. Unlike the Trolls' story, the Tauren very much were a divine creation. The Earthmother (who could be the Tauren name for one of the Titans, perhaps) created the world, and with it the Tauren. Wowwiki has some decent information on all of that stuff.

Are the Eredar another seed race of the Titans, just from a different planet? If that's the case, would that mean the Draenor Orcs were Titan seeds as well?

We know absolutely nothing about the Titan involvement on other worlds. Anything would be a guess. The only Eredar and Orc connections to the Titans that we know for sure is that Sargeras or his Legion lieutenants have controlled them at some point. We've no idea if the Titans created all life, or just made some planets all pretty-like.

When-oh-when will we see Spellbreakers as a class? I can't help but say that the idea of an anti-caster, buff/debuff, hybrid class intrigues the bejeebus out of me.

Oh gosh, the last thing we need is another anti-caster class after Death Knights. While I, too, like the wow powerleveling idea of a buff/debuff based hybrid/support class, I don't think we'll be seeing Spellbreakers. Personally, I want to see something more like the vrykul Runecasters for the next Hero class. Buff/debuff based, tons of support/utility, and if given some good healing capabilities? Perfect hero class! Eh, maybe not.