How does the transmog stuff work? I haven't really looked into it, but I got a really cool weapon from a Grove Warden run that I'd like to keep the appearance of even if I get something with better stats next expansion. Is that possible or is it only certain styles that can be kept?
Basically, currently, you need to have the item whose appearance you want to copy somewhere: inventory, bank, void storage. Starting with 7.0, each of those appearance will be recorded on an account-wide wardrobe once you acquire it (i.e. it becomes bound and not tradable), and you'll be able to disenchant/sell them.
You can apply the appearance of any item you have on a similar item: same slot, same material (plate on plate), subject to item limitations: you can't apply the appearance of an item you can't use because of class/race/faction/rank/achievement restrictions on the item. So, for example, you can't use mage sets looks on a priest, even if they're both cloth (except for items that are intended for a class, but do not have a class restriction explicit on them, like old dungeon sets). The additional (current) restriction is that you can't apply the appearance of a legendary or artefact item on another, but you can override your legendary/artefact item with another non-legendary look.
On 7.0, you are supposed to have your entire bank content be added to your xmog, plus any item that you could use from quests you've finished, even if you don't have them. For example, if you're a warrior and you've done the
Evidence Collection - Quest - World of Warcraftin Westfall, you'd get the Mail bracer unlocked, but not the leather or cloth item, but if you did the
Rise of the Brotherhood - Quest - World of Warcraftone, you'd unlock all of the weapons and can use the staff for your mage. But if you did that quest as a mage, you'd have only the staff and dagger appearances, and the polearm remains locked.
Any stuff you got from drops and sold back will have to be farmed again. And if the item isn't intended for your class, its appearance will not unlock. So, if you're farming Icecrown Citadel with your DK and a cloth robe drops, the robe will not unlock. "Because it would be unfair for the cloth wearers who would be unable to equip the plate". A lot of people are petitioning to have any bound item unlock, no matter what, but they haven't budged from their stance. Yet.
So will current salvage boxes still give the same green t mog rewards once the prepatch and new system launches? That seems to be what you guys are implying.
Yes, the current crates remain unchanged, the Salvage Yard will simply drop new crates without the green/blue/epic BOEs, those will just have the follower upgrades plus the blue BOP set.