она всё нарисовала--does this mean she is very accomplished and has drawn in her life all sorts of things, or does it mean she has finished a certain drawing task (such as making drawings of all the insect specimens collected)?
она всё рисовала--would this mean "she used to draw everything" (but not any more)
Which form would you use for "When she was younger, she drew everything. Now she just does people" or "Yesterday she drew everything we asked her to"?
I generally think of perfectives in the past tense as translating to "(insert verb) is finished" in English. Thus, I would naturally translate this sentence as "My sister has finished drawing everything". Would this be an accurate translation of this sentence? If not, why not? Also, is my idea of past tense perfectives accurate?
This is a valid translation if you want to stress the meaning of 'having finished' something. However, perfective verbs can also simply mean a one-time action, as opposed to continuous or repeating actions. For example, you can describe a sequence of actions with perfective verbs: Я надел костюм, вышел из дома и пошёл на работу. This should clearly be translated with Past Simple.