I'm not high-end arena, but here is some theorycrafting for you to consider:


If you had them on castsequences, and different keybinds that could work.
You'd have to be able to press both keys easily at the same time.
Something like:

/castsequence Earthbind Totem,,,
/castsequence ,,Thunderstorm,

And then move the spells along (or move the comma's) for each shammy.
You could also put them into the same sequence so one shammy does each on a keypress.
I personally prefer separate keybinds, as you may want to chain one without the other at times.

As far as the fear bomb, the "Click to Move" and "Interact With Target" keybinds are amazing for world pvp.
I'd imagine you'd have good results in arena too.
Your team has been fear-bombed. Tremor will tick in 1-3 seconds.
As soon as it does, click interact - which will have each team member turn to the target and then run towards them.
Now click your forward/backwards movement keybind to end the movement.
And click your Flame Shock + Elemental Mastery + Lava Burst macro.
There is a 0.5 second macro in the pvp section, forget the posters exact name, but he's amongst the top in 5's in his battlegroup.
You could even have your team all run at one toon, via Inteact/Click to Move, as a method of having them all run at once towards the same destination for a regroup.