New to puts (don’t bash me to hard hehe)

Hello, I recently bought a TSLA Feb 22, 815 put

I’m a complete noob and did this without much researching so take it easy on me,

3 questions,

-If it hits 815 before Feb 22nd is it automatically exercised, and would I receive 100 shares?

-If it hits below 815, do I continue to get further gains if it goes lower or is it automatically exercised at 815?

-What happens if it hits below 815 (and doesn’t get exercised automatically) but then it goes back up over 815 before Feb 22nd?