Autobiographical Fiction and Complete Characters

I've been asking Tom heaps of questions about writing. And I think I might be getting out of control.

For example, I've been wondering about the idea of starting from autobiography and building to fiction. I've been asking things like this:

Let's say an author is creating a character the core of whom is born from a part of the author's real life character. And let's say that character overlap (the part of the author that character represents) is the key aspect of the fictional character. To what extent does the author have to intentionally fill the fictional character's excess character space? To what extent do authors think about doing things like filling character space vacated by partial character basing? And to what extent should or shouldn't they? Can characters survive (achieve greatness) only half imagined by authors? Or must authors imagine complete people (part author, part something else)? Or is it even remotely close to possible to imagine and write about complete people? Can we even communicate about ourselves as complete people? Do any of us ever know ourselves completely?

I'm pretty sure there don't exist straightforward answers. But, apparently, I continue bugging Tom. Poor guy.