Re: the idea of hell being behind the exterminations
I know a lot of people disliked the idea that it was Lucifer behind the exterminations, but I always felt it made a lot of sense.
In a good portion of his depictions, Lucifer despises humanity, for various reasons. Therefore, him wanting to destroy/torture/punish human souls more than they're already being punished would make sense.
The exterminators could look like angels because a) shapeshifting, or b) they're the demons/fallen angels that fell with him when he was cast out of heaven, and that's what fallen angels look like (based on the common lore that the original demons were fallen angels)
There would also be the complexity of the fact that Lilith was once human herself. This could either be the cause of their marriage falling apart (Lilith being tired of hearing 'but you were different') or if the two of them were the lovey dovey couple they were originally intended to be, it could highlight Lucifer's hypocrisy.
Basically, in my opinion, Lucifer being the one behind everything would have been more interesting than another generic "heaven were the villains all along" plot.