My approach has been to fully embrace being a magic healer and the ability to heal through damage when solo.

My healplar is at her best standing back healing/supporting her group, but WBs are a good example of how she can flip on a dime. If there is a tank or even melee dd or two on the WB, she stays back and focuses on heals/support to keep them alive and sustained. If, however, the only others on the WB are ranged bow plinkers (for example), she charges in to the boss's face and hold him - almost like a tank without taunts. To do this (or even solo a WB), she needs big sustain for sweeps (Seducer, EleDrain, 1800 sustain, Channeled Focus, Spell Power potions). With that she can stand in Channeled Focus and sweep all day long. She does moderate dps while getting stunning self-heals. She does 'read' the boss carefully and moves in/out of her Channeled Focus aura to avoid red/stupid. She also wisely uses block/bash at the right time.

Though she can handily solo a WB, there is nothing classically 'tanky' about her. she runs 5(light)/1/1, all attribute points in magicka and carries 18.5 health on blue food. Very similar set up to most group healplars.

Yes you will in dungeons certainly. In the wild, it used to be that you have to do something like either 5% of the damage or of the healing to get the exp and goodies, but I don't know the exact rule.
I spam healing when doing dolmens when I can't see a thing due to lag, and I get the exp.