Shift 1 and Shift 2, get you two different main bars, within the default wow client.
Shift 3 through Shift 6 switch the main bar to any of the other six, but these can already be displayed via Interface - Action Bars.

You'll pvp best with all shaman's.
They have a lot of things going for them.
That isn't to say others don't have potential.
As far as world/battlegrounds go, anything works.
Arena, especially at higher ratings force more ideal compositions.

Shammies have:
Mail armor and shields.
A lot of controlled burst.
Strong support heals.

In general, you wouldn't want click sequences for pvp play.
Probably go with... Flame Shock, Lava Burst, Chain Lightning, Lightning Bolt, Purge, Lesser Healing Wave as the main spells, each on its own button.
Have a default totem stomp macro, for 4 of each totem.
Have a few castsequences, either wow based or within inner space for things like Tremor, Earthbind, Fire Nova, Fire Elementals and Thunderstorm.
Have some things where each can cast/drop immediately, such as Grounding Totems.

Inner Space gets you a strong FTL system, which I'd highly recommend for pvp.
Not sure that you'd want the automatic follow or strobe follow enabled, probably better to activate via an easy to reach keybind.
This way, any toon can lead as easily as any other.
You can Flame Shock a toon and then another toon, without a sequence getting you the next spell automatically.
You can move back to the first target and Elemental Mastery - Lava Burst, without needing to re-cast Flame Shock etc.

You'll want "Click to Move" enabled across the board.
As well as an Interact With Target key.
Possibly set InnerSpace to broadcast this to everyone other then the current character.
If you go this route, you'll also want something for everyone to interact, so you can recover from Fear bombs.
That way, any toons out of range can interact/move into range, but your current toon doesn't run in.