Mark? Take aim
Replace? Fair game
Research the first hint maybe?
Hint for line 2:
it's referring to a person.
Replace the ? With a colon : on the strength of replace fair game and crohns inflamed.
Mark: Take aim. Colon is a punctuation mark and concentrates attention
Action: Misnamed. It is kind of yes but not really a Riddle: Word game. Or, instead of a question and answer, each line is now an imperative statement.
Usage: Explain. Yes, this is what I am doing now.
Replace: Fair game. Thank you for the permission!
Crohn's: Inflamed. Because Crohn's is colon inflammation.
I got nothing for hint 2