I am afraid I shan't be able to answer the questions
"I want to know everything" is an incorrect test strategy. You can never know everything (maybe the professor does), besides, it is not really necessary either. If you master 70% of the subject-matter, you will probably get a seven.
But if you try to know "everything", you are imposing an impossible task on yourself. This may be the beginning of interfering worry. A more realistic question is: "Is my knowledge adequate?"
I want to continue with

  • I still think that I ought to know everything before/during the test

  • "Do I know enough"

  • "What shall I do if I do not know an answer during a test"(information on a proper test strategy)