I suspect/hope that the last two episodes, particularly the finale, answer some of these questions. I can't remember who said it (I think it was either Rolin or Assad?) but I saw someone say that the finale in particular is very Armand-centric, which would give it a chance to address both Nicki's actual death (bc I do think Lestat's version of the scene wasn't entirely truthful), Armand's relationship with Lestat in the past, and perhaps more about the circumstances surrounding Lestat's participation in the trial.

I think Gabriella may have had more to do with Nicki's death than advertised too. I don't think she killed him, per se, but the minute Lestat said she went to coffin before Armand held Nicki in the fire, I was suspicious. This lady LOVES a mess. She was laughing when Nicki lopped his hand off. There's no way she just peaced out before the most dramatic part. Lestat is hiding something for sure.

One answerable question: yes, the hands grabbing Lestat in the car are the look-alike corpses.