1) Mastery on gear gives you one bonus. That bonus is the third passive (the unique one) in the tree in which you've spent the most points. In the examples we gave, those are Absorption, Radiance and Runic Power generation.
2) Ferals will have passive bonuses that say Cat: melee damage done, Bear: damage reduction. For death knights we have a different plan in mind that we're not quite ready to discuss. DKs are undergoing some slight changes so they aren't so GCD constrained and are less limited by rune cooldowns.
3) Assume you only get the passive bonuses for the tree in which you've spent the most points, and there is a ceiling per tree (which could be something like 51-55 talent points). If you spend more points than that in a tree you still get the benefits of the talent. If you spend points in another tree, you are benefiting from those talents instead. Unless you try to make say a 40 / 36 / 0 build, you shouldn't be losing passive bonuses.
If you turn level 10 and spend 1 point in Discipline, you are now a Disc priest. You receive the Disc talent tree passive bonuses and mastery rating on gear benefits your Disc passive bonus (Absorption). If you reach level 85 and have 70 points in Disc and 6 in Holy, you are still a Disc priest and the same rules apply. If you change your build to 51 Disc / 20 Holy / 5 Shadow, you are still a Disc priest.
4) They are weak now and the intent is to keep them that way. We aren't trying to nerf them any more than they are today. If we want to make sure Resto shaman can do big Lava Bursts, we'll give them a talent or something to make that happen. We don't want Resto shaman to Lava Burst anywhere on the scale of an Elemental shaman. Again, how they perform today is pretty much the target for where we want to end up.
Looks like they're designing it so players can't receive the benefits of more than one talent tree at a time -- it's whatever tree you've got the most points in, and there's a ceiling per tree. It's also reassuring that they're keeping feral druids and DKs in mind when designing this, although now the question is just what are
they doing to DKs? Check out yesterday's post
, which includes a more detailed look into just what these talents are going to look like, and stay tuned for more information as we see it!