They were accustomed to harsh ....is the answer. In the excerpt, Frederick Douglass is surprised to see a kind gesture from a white person, even if it is just a child because he is so used to being treated badly. Seeing an innocent face cheered him up.
I believe the answers are "the air was in the early morning; like the flap of a wave; the kiss of a wave" and "on waves of that divine vitality" because they both mention waves (water) let me know if thats correct hope it helps!
