-How are multiple auras of the same type calculated by the game?
> their skill levels stack, so dual dream would be 1x level 30 holy shock, hoj + dragon + dragon would be 1x lvl 44 holy fire, player aura does not stack with this (the highest aura overrides the other iirc)
-Is it a bad idea to use HF and HS together?
> yes its really bad, holy fire only shines if you use all 3 pieces, holy shock only shines for a tesladin where you use enigma and grief. so either go pure holy fire for pulse damage which is decent on p1-p3, or play tesladin and go more teleport/zeal focused damage.
-Can I use two different resistance sunder charms simultaneously?
> yes you can use as many as you want
-Is zeal always better than vengeance?
> yes vengeance is a horrible skill, ive theorycrafted every possible outcome with this (even with fire mastery and lightning mastery and cold mastery on a sorc with kingslayer, the skill is just very bad both on paladin and on any other char)
-Is Crescent Moon as effective as people are saying?
> can be useful for a tesladin but it doesnt outperform grief, its a nice budget option until you get grief.
-Is there anything else I should know before building an auradin?
> most of this answered in earlier answers, both pure tesladin and holy fire pulse paladin will be decent in hell, for higher player count i would personally play tesladin over holy fire, and for lower player count density clearing holy fire is nice, like cow runs.