Its nice of you to do all this 'extensive exceling' to find that you only need 3 shamans, but I cant think of any encounter where you need all those resistance totems dropped in 1 fight. Therefore 1 shaman can provide you with 3 different resistances. If you choose a paladin tank you will also have frost res, fire res and shadow res aura on him.
With that said you shouldnt pick your team based on resistances anyway as the only resistance that is majorly helpful most of the time is shadow res as it helps reduce the chance of getting feared.