Please help with homework Hamlet Act II, 2.3: Explain the following wordplay by Hamlet

19. Explain the following wordplay by Hamlet (to Polonius): Let her not walk i‘ the sun. Conception is a blessing, but as your daughter may conceive, friend, look to ‘t.

What word does Polonius use (unwittingly) later in the scene to comment on Hamlet’s way of speaking? How does it make Hamlet’s three lines above even more relevant?

20. In the same scene (Hamlet and Polonius), show three other instances where Hamlet uses humor to frustrate his enemy.