The manga explains more. Read that instead. Waiting for the Ultimate OVA to catch up with the manga is going to take a while since they're starting fresh from the start.
The best solution: Read the manga. It's a hell lot better than that shitty ass anime. Hellsing the anime sucks balls. For lack of a better term, that's a fact. The anime series is a horrible representation of the manga. The ending was rushed since they had to practically invent their own ending since the manga was being developed at the same time. The Major is hella lot cooler than Incognito and the anime-version of Anderson is an insult. Oh, and Incognito is a wimp compared to even Tubalcain Alhambra.