Just me or does the Resto Shaman build seem rather...dry?

For Chain Heal, a convenient, math-free implementation could be:

Roll a number of dice equal to rage damage bonus.  Line them up and sort from high to low.

Heal the primary target for the total (this could include your modifier), heal a second target in range of the first for the total omitting the lowest die, heal a third for the total omitting the lowest two dice, etc.  

Concerning the (lack of) limiting resource problem, it seems like one could imagine that using soothing water and healing is not channeling rage, but competing against it, such a Resto shaman might need to alternate between generating rage through damage or other resource management, and spending rage to heal.  Or (equivalently) they enter rage with a Water Shield containing a certain number of charges, which eventually requires replenishment as they "dry out" from healing.