Aura Guardian + Herald of Purity

I'm going to build a Guardian mainly focusing on Auras.

I'm wondering whether it's enough to use Herald of Purity as my main dmg skill, if i use some gear and passives to buff it somewhat in addition to the powerful auras. (obviously i would need a damage skill to summon the sentinels in the first place.)

Or would i need other ways to do damage as well so as not to kill things terribly slowly? Herald of Agony, other minions or a direct damage skill. Ethereal Knives, Arc, Dominating Blow, Spark or Ball Lightning seem like the most popular damage skills for Guardian these days, so possibly one or two of these. I would prefer to use the minimal amount of passives and gem slots that i can get away with however to focus as much as possible on auras.

While on these subjects i have a couple more questions:

Are there some minions, that doesn't come from gems, that are particularly good?

Is fork good with arc and after arc chains does every "hit" count as a hit for the purposes of stuff like mana, life or ES gain on hit?

I've never really played a build where minions are a significant part of my build, so this may sound like a rookie question, but when you have, say a golem skill, that says minions gein 38% increased life, does that apply to all minions or only the golem summoned from that skill?