> Do anarchists reject
> all hierarchy? Or just unjustified forms?
The latter. It's often termed "illegitimate" in anarchist literature.
> In a student/teacher relationship, doesn't the student often
> temporarily accept the teacher's statements in a dogmatic way, before
> getting to the point of questioning it? (Or just plain accepting it if
> it's not that important?)
Not sure what happens as a biological or epistemelogical matter, but anarchism would not endorse dogmatic acceptance of a teacher's statements.
> In largely propertyless teams like a free software project, don't
> people evolve certain voluntary hierarchies?
Sure. People can legitimately respect other's expertise.
> Is anarcho-christianity a contradiction in terms, even though someone
> might believe anarchism only applies to human relations rather than
> supernatural ones?
I believe so, but I don't believe it to be so important as to require dissassociation, particularly because the god of the anarcho-christian doesn't typically ask anything of him or her and so doesn't really control him or her as an authority. If that were otherwise, I might take a different view.
http://www.spunk.org/texts/intro/faq/sp001547/index.html