Dracula's Events in the Hellsing Story

Really confused on this subject.

Did you originally intend Hellsing as an homage to Bram stoker's Dracula?
HIRANO: It's not a sequel or anything, but in Hellsing's world, the events of Stoker's novel indeed took place.

I know the quote in which Hirano said that the events of Dracula, the novel, do happen in Hellsing, but there's numerous contradictions that shake his claim. Or alternatively, we can take "events" as something not literally meant, but the key events happened, albeit in a different way.

A lot of people assumed John Seward's name (written as Jack) and Harker's removal to be mistakes on Hirano's part, but four members of the group (presumably Seward, Holmwood, Quincey, and Abraham) have been shown consistently in two separate flashback appearances (vol. 8 and vol. 10). There's not a "fifth" member, so we can safely assume that Harker is out of the picture in Hellsing's retelling of Dracula's story. So, who replaces Harker?

【1899年】
不死の怪物となった“伯爵”がトランシルヴァニ アの居城で、アーサー・ホルムウッド、キンシー・モ リス、ジャック・セワード、エイブラハム・ヴァン・ヘ ルシングらによって倒される。一連の事件の際、 アーサーの婚約者であったミナは“伯爵”と出会 い、彼の血を飲む儀式“血の洗礼”を行なった。 その後“伯爵”は王立国教騎士団一ヘルシング 機関において様々な改造・術式を施される。

The booklet of OVA X claims "一連の事件の際、 アーサーの婚約者であったミナは“伯爵”と出会 い、彼の血を飲む儀式“血の洗礼”を行なった" in a section where it recited the timeline of Hellsing (which included Dracula's story), and seems to be in line with Harker's omission in the manga, so he's replaced by... Arthur Holmwood? Nonetheless, the OVA's revision of events seems to be the most consistent with the manga reciting and should safely be considered canonical; at least that's what I think. If not, then this is the OVA canon of the story.

So now, what's the difference?

• Dracula's powers and how vampirism works.
• Dracula sought and is infatuated with Mina.
• Jonathan is replaced by Arthur.
• John is renamed Jack.
• Mina's name, since the start, has always been "Harker" and not "Murray."