I play a resto/ele shaman, but I mostly pvp with him. Resto is phenomenal for pvp healing, you have great single target and multi-target heals, albeit not as strong as a paladin's or druid's, respectively. That said, I do find resto pve to be boring as fuuuuuuuck, it largely amounts to either mashing healing waves and canceling them halfway through ( or not, this is wotlk, who actually ooms anymore) or mashing chain heal. I guess it's a bit more interactive than that in 5 mans/leveling, you can juggle totems/interrupt/assist dps or w.e, but once you hit raids it's dull.
That said I really do love shaman pvp. Love love luuuurve.
As far as addons, I like totemtimers, and I know some people swear by shaman friend, but I've never really needed it. Mousover macros are great for healing, and very simple to write. Just #showtooltip Healing Wave; /cast [target=mouseover] Healing Wave etc etc etc.