Cronos 1993 film, question about the device?

What exactly was the device DOING when it was being used, I think the last time it is used we see something inside like a worm? Is it removing or injecting something into the person?(We see the protag start it and then slump in joy like a heroin addict).

Why were the people made immortal turning into vampires?

Bug vampire juice. Probably similar to what causes the “infection” in other movies/books/mythologies.

They’re probably immortal because that’s a common vampire trope?

So the device really just turns you into a vampire basically?

Did they ever say WTF the alchemist was doing in that collapsed building? They said he had marble like skin, so presumably he was so deformed from half a millennium of immortality that going out in public would seem difficult. Why did he leave his gruesome vampire mansion? Later in the film at the New Years party there were some architects discussing load bearing or something, I was wondering if it was connected.

It was a scarab beetle, an ancient Egyptian symbol of death and rebirth.