What I would like from this thread is stuff that people can confirm from PTR testing of 5.4. Post anything that people seemed to have questions on and that you have found out so far.
For example, I can personally confirm how the Ele shaman 2pc and 4pc work.
2pc: With my total 7 charges of Lightning Shield, the debuff that the target gains (called Elemental Discharge) reads "Fire and Nature damage taken from the Shaman increased by 10%.". The debuff lasts 14 seconds (the timer seems to start at 13 seconds but it is safe to assume that the extra second is included already).
4pc: The pet called Lightning Elemental has 1.2mil HP and 99k mana. It casts a spell called Lightning Blast that seems to have a 1 second cast (not too sure on this). Lightning Blast (for me) deals about 15-20k non-crits and around 30-40k crits. More than one pet can be active at a time (I've seen a maximum of 3 so far) and the spawn chance does not seem to have a particular unseen cooldown. This pet seems kind of good because at least we won't have to worry about pathing, but its spell has a 40 yard range and they can't cast while moving (but they move fast actually). SPOILERS: They look like air elementals you could see in The Vortex Pinnacle or ToFW.
Also, Call of the Elements does not seem to work with the new Fire Elemental Glyph.