"Also of note, you only get one set of passive talent tree bonuses: the tree in which you’ve spent the most points. Sub-speccing in another tree will not net you those bonuses in addition"
copied from the shaman updates posted on the front page. If shamans aren't getting sub spec mastery bonuses, I'm sure this is how it will work for all classes - whichever tree you have the most in is the tree you get mastery bonuses from. You mentioned "sub spec" bonuses a couple times in your post which probably won't exist.
Also, I could have taken it wrong (though other people I've talked to seem to think the same thing) but I believe the way the Enrage mastery was worded it indicates that it will buff the ability's RESPECTIVE function, not giving a damage buff to each one. ie deathwish buffs damage more, enraged regen restores more hp, bloodrage gives more rage, etc. Being a preview and worded rather vaguely it's impossible to know for certain what is intended though.
Edit: decided to copy in the exact quote
"Enrage Intensity: Every benefit of being enraged is increased. This includes doing more damage/healing/ etc. from abilities like Bloodrage, Death Wish, Enrage, Berserker Rage, and Enraged Regeneration."
the phrase "every benefit" leads me to believe it is the seperate effects of these buffs that are increased. There's also nothing in there saying "enraged effects increase damage", "damage" is merely the first one listed off of the items that have the potential to be buffed, which clearly would refer to Deathwish.