In regards to how to temper without a Primal, if I remember rightly Ferne personally answered this particular question at the first Fanfest, explaining that when a Primal is summoned, the surrounding area is bathed in it's elemental essence, which lingers even after the Primal is defeated. That essence is rather like an aetheric residue that is collected by the beastmen who summoned the Primal and store it, and then use it to temper more followers even without the Primal being present by immersing their prisoners ritually in it. Naturally this process is imperfect and may require several attempts to fully temper the unfortunate - this was shown during one sahagin beastquest where the player is racing against time to free a group of captured Maelstrom soldiers who are being 'drowned' at the water's edge - you can only save two as the other two have already sadly succumbed to the aetheric immersion and are now 'drowned' (and thus, have to be put to death as they attack you immediately).
This also explains why each beast tribe seems to have structures that harness that element (viz the amalj'aa beacon towers in Zan'rak/Zaha'rak, the crystalline orbs in the Sylphlands that spew out violet 'fumes' that are even stated as 'corrupting the forest around them with Ramuh's taint', the tidal pools and flats in Halfstone, to name a few, these are all used to contain the aetheric left-overs of each Primal for the purposes of tempering new followers even if the Primal is not around. Really, this Primal-residue is essentially the same thing that SMNs use when first evoking an egi form, it's just being used in a different way.