Thinking about rolling a healer over here on Mid side. One reason, I never played Mid on live but always had the urge. Another reason is because I really want to play the support/healer role in RvR.

I was looking for some suggestions on leveling strategies commonly used by healers. What type of specs are commonly used at 50 for RvR in groups? Any help would be appreciated.

As for leveling a healer - their is NO - and I mean NO - faster way than to spec Pac and duo with a Spiritmaster. Focus pulling is insanely, at times almost nerf worthy, fast exp. Finding a SM to group with may be difficult at times and at low levels Healers are far inferior to Shaman due to endo buff...that being said, once you get into the mid 20's where large grouping is common place a healer is ALWAYS welcome as they spec higher in mending than shaman and POM = win for healers and nukers.

Toward end-game, respecing to Aug is commonplace due to celerity. It is up to your preference entirely. Pac gets spec line mezzes and instant mezzes and POM (power regen) where as Aug gets to spec into their buff line and gets some self buffs and the coveted attack speed buffs (base buff and celerity timer buff - stackable of course)

RvR - all about play style. Once leveling is out of the way it is up to what you want to do. Help melee turn into a blender - spec Aug for a near 50% increase total in attack speed. Help with crowd control - spec Pac for the array of powerfull mezzes and instas. In either case - spec high enough into mending to get some good group healing (I suggest at least the 1st spread heal or "smart heal").

Hope that helps

Another spec option if you play when the server pop is low and this force you to exp alone, you could think about speccing full aug till 20 at least... i've started an aug healer too and i can chainkill yellows with no rec time!
However there's a tri-spec option too, but i don't know if it's viable on uthgard..

Dont try focus lvling, u will ve problems finding a sm and it is sooo unstable that u ll be wiped several times and if u dont know midgard very well u will not find any proper spot for doing it. Go mainly aug, rest mend for leveling, invite a shaman and as many meele dps as u can get. Quiet easy in mid. With 50 u can respec to either aug RvR spec or Pac RvR spec.
Regards
Edit: Push alchemy with ur money and craft pom pots, then u ve the pom u dont get since u spec aug instead of pac. Pac is quiet useless then, since the only thing worth it for PvE is POM.

OR, you could just save your money and respec at level 40 and start going towards your final spec

As pac or aug you will level very fast. People prefer healer (doesnt matter pac or aug) than stay afk or die.