The Abyss: It probably hadn't formed yet. It could have been a result of the Pillars' corruption.
Vorador's whiskers: His whiskers are the least of what needs to be explained about him. He shouldn't even be alive in BO2 seeing as Moebius had him guillotined.
Treading carefully: Always a good idea in Nosgoth. I always thought the EG saying this to Raz in SR2 (shift to spectral under the pillars platform during the first visit there - he'll say it eventually) was rather funny; almost like the EG is warning him not to step on one of his eyeballs or something.
Blood founts: Probably served their purpose, along with the BO1 spirit forges, moon caves, and SR1 warp gates.
Vorador's brides: Probably in his mansion, which we never saw in SR2. Some of the female vamps in the background at Sactuary (BO2) looked and behaved fairly bride-ish to me.

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