[X] Gawain (Walter's Suggestion)
He was found in Britain and so will have a proper badass British name.
[X] Seras Victoria
As a baby Primarch- no
because he's a baby Primarch he needs to have someone around who will teach him and remind him that even if he's a superhuman angel man he's still human. I honestly believe that Seras would be a fantastic mother (she and Integra definitely win in any "my mom is better than your mom" argument) and is just the thing a young, impressionable child needs. Plus
@Cjdavis103 does bring an interesting point up when it comes to vampires.
[X] Martial
Teach him to be a badass in combat
[X] Diplomacy
People skills are very important
[X] Stewardship
As the Hellsing heir its important to know how to run said organization
[X]Pieity
Having a spiritual side, especially in 40k is important
[X] The Hellsing Library
He needs to know the people who bleed and died for the knowledge he is going to utilizing in the future.
[X] Alucard's Basement
Lets be honest its important to have a somewhat positive relationship to the most powerful being on the entire planet.