In the first case, you don't have too much space to write a detailed character analysis as you have to write about all elements equally.
Foils - the role of these characters is to contrast with the majors throughout the story.
Faith is the opposite of Buffy, Spike is the opposite of Angel, Draco Malfoy is the opposite of Harry Potter, etc. These are people with double-nature, and multiple characters in their mind are all great examples of 3-dimensonal heroes.
Read the original story to find some proper quotes to answer these questions; make sure to cite every quote properly.
Choose something like: We recommend using extra study materials and prepared templates to write a character analysis essay every teacher wants to see.