The doctor in Marvel comics often serves as a healer or a source of medical expertise for the heroes. They might also have a hidden agenda or special powers related to medicine.
The number of Marvel comic heroes is constantly changing and growing. As of now, there are well over 8000 characters, but new ones are always being introduced.
I don't think so. In the comic book universe, characters usually operate within their own storylines and don't have the realization that they are fictional creations. So, Doctor Strange is no exception.
Well, Doctor Strange 2 takes cues from multiple related comics, combining and adapting different plot points and characters to create a unique cinematic experience. It doesn't have a one-to-one correspondence with any particular comic issue or series.