He was referencing the pseudo-Aztec religion he made on Belu. Cult of Blood or something other, I think?
Yes, the Blood Cult on Beluaterra.
This is absolutely correct.
If Chénier hadn't insisted on the Aztec-inspired naming and such, I honestly don't see any good reason why his original Blood Cult ideas wouldn't have fit Dwilight just fine. From what I can remember of the basic principles, they were pretty abhorrent to modern Westerners, but would be relatively reasonable to a medieval non-Abrahamic society.
Because Tom said he didn't want non-european-inspired religions and concepts on Dwi. If it was just the names, then sure, they could have been changed. That was never the issue, though, as far as I ever was made aware. Medieval abrahamic societies was precisely what he wanted.