So I guess the only time Dracula ever used a vessel was in 1479?
I think so. And it turned out to be a bad idea, it seems. We learn on Curse of Darkness that one needs to be both influenced by Dracula's will and sufused on Dracula's magic to work as a vessel. On Order of Ecclesia there's only one person that could potentially fit the bill: Albus. Shanoa is infused with Dracula's magic, but not influenced by his will. Barlowe is influenced by his will, but never once sufused with Dracula's magic (remember: he never once wears Dominus!) before he dies.
We know in this series that being influenced by Dracula's will and being infused with his magic are two separate, very different things, and again, that
both must take place so the person can become a vessel for Dracula. Barlowe fits one, but not the other.
Chaos is the personification of the evil in human's hearts and it's what causes Dracula's evil side to be amplified. Regarding what actually constitutes Dracula's power, from what I understand, this consists of two things: the Power of Dominance which is an inherent part of Dracula's soul, and the various abilities he accumulated over the years.
I'm aware of this, but this:
Chaos is not the source of Dracula's power. It's the personification of Dracula's will/intention (and all the negative emotions of humans).
Doesn't appear to be correct. Mostly because the opposite is
precisely what the Ricordanza novel says: Chaos is the embodiment of humans' collective evil AND the source of Dracula's power/regenerative cycle. I'll be pasting a piece of Shiroi's translation:
“As I’ve said, I would equally gain control over the human world and the source of Dracula’s power, chaos. I do not intend to obey someone else’s mind aside from my own. That includes you [Death] who were born out of chaos.”His Castle is the symbol of his power/magic, and was woven out of Chaos, exactly as Alucard says in Symphony both in japanese and english. I don't have access to Aria's japanese script (yet), but I do have access to Dawn's japanese Library, and it also confirms the same: The castle is what is the symbol of his power, not Chaos. Once it was locked within the eclipse, Dracula was torn off from his magic (which again implies that Chaos is Dracula's power source with the castle serving as this power's symbol):
ドラキュラが完全に滅びる事になった戦い。
ノストラダムスの予言、恐怖の大王はドラキュラを意味していた。
しかし、この戦いで日本にある白馬神社の神主の力により、ドラキュラの魔力の象徴であるドラキュラ城が日食に封じられる。
これにより、ドラキュラの魂と魔力が引き剥がされ、復活の運命から解き放たれた。
Furthermore, Chaos can't be a creation of Dracula, because Death existed before Dracula was even a thing. Even if Shiroi has embelished the line above about Chaos being Dracula's power source (which I don't believe to be the case), the novel confirms multiple times that Death was born from Chaos along with all other demons and monsters, which also have existed before Dracula did, as we know from Lament of Innocence.
I'll be checking the japanese script of Aria to learn more about this.