Humanity questions-
Killing a human can cause a loss of humanity. It is mechanically not guaranteed, especially as you lose humanity. The lower your humanity gets, the harder it is to lose, because things just don't trigger someone if they are a sociopath verses a normal person. Most vampires are sociopathic to greater or lesser degrees. Sharon, who is trying very hard to maintain her humanity is an example of someone who would lose humanity by draining a human dry, or a vampire dry.
Diablerie/Amaranth
This is a life altering event. One can easily become addicted to doing it. It is hard to express how much it can affect a person, but I will try.
The first part of the act is selecting your victim. Usually for some type of gain, either knowledge and abilities, or lowering your generation. It is possible to have more than one vampire participate in this, if the proposed victim is significantly more potent than any of the Diablerists.
Second is the pacification, usually by staking through the heart. This allows the victim to retain consciousness but lose the ability to move. If the vampire victim is very powerful, further methods of securing them might be necessary. Some gruesome ones are removal of limbs, removing eyes and tongue, nailing them to the ground or secure surface with large spikes etc.
Third, drinking the vitae, draining all of the vitae starts the diablerie process. Once that is complete, the diablerist continues to struggle with the victim in a war for their soul's blood. The victim makes opposing rolls of the dice to resist this. If the diablerist can not complete this, then the victim will go into torpor and remain there until healed. So assuming that the diablerist wins, they suck the soul's blood, along with the knowledge, lowering of generation and or gaining powers, and erasing the existence of the victim. No soul to go into the Wraith game. No afterlife. Devoured by the diablerists. Now if the victim is sufficiently powerful... it is possible that they destroy the will of their murderer and take over their body. (usually 4th generation and lower) As an example that is not in Rebirth but is in VtM, both Augustus Giovanni and the wizard lord Tremere failed to properly diablerize their targets. (Giovanni-Cappadocius, Tremere-Salout).
I suspect that if any of the vampires we have seen were to attempt to commit diablerie on Vision Girl, she would either resist them or take them over.
The above takes a very serious toll on humanity. In VtM there were multiple paths that were in existence (prior to 5th edition which is SHIT) that functioned like humanity to stave off the beast inside all vampires. Some were even pro diablerie and pro devouring and extinguishing human life. These vampires could seem to be "normal" to a degree, but were often quite alien to the human mind.
New locations-
I am betting we do see the start of the new Night Club. Also I am betting we see City Hall or where ever the power structure of the town is held. I am also betting that Sharon has plans to make Scottstown into a much bigger burb than it currently is.
The other possibilities I can think of is a completely reworked home for Sharon, the Nos hide out, the MC's private place, since he probably needs one to keep Laurie and Sharon off each other.
Have a great Cinco de Mayo!
Peace