Chapter 14, 15, and 16 talk about factorial designs, repeated measure designs, and mixed design. Explain the difference between these.

Chapter 14, 15, and 16 talk about factorial designs, repeated measure designs, and mixed design. Explain the difference between these. Give specific examples that you would choose one method over the other.
Through Chpaters 12 - 16, the author has mentioned homogeneity of variance and sphericity. Why must we considered these factors in General Linear Model (GLM) statistics?
Why can't you use any of the statically analysis tools and technics we have learned so far on categorical data?
Explain in detail a "Goodness-of-Fit" test and when and why this test would be used versus any other analysis test?