what factors could affect the amount of time spent in each phase of mitosis? I thought maybe it had something to do with the amount of genetic material needed to be replicated, but now I'm not sure.

Answer 1

This is not my field, but this web site may be helpful to you in answering that question.
http://www.teachersdomain.org/resources/tdc02/sci/life/stru/dnadivide/index.html

The amount of genetic material certainly has a lot to do with it. So does the presence or absence of a nucleus.