Rember that the fuku is presentes as a kind of curse, and has been with Oscar's family since his grandfather's time in the Dominican republic. So a good way to find places where the fuku is shown in the novel would be to find the ways in which Trujillo, his regime, and the after-effects of his regime have affected the family. I would focus on the grandfather, Beli, and Oscar first (because they're the easiest/most obvious) and then move on to Lola.
As for the second question, is Oscar really "hesitant" with love? It seems to me that he jumps in with both feet, even when he knows that the objects of his affection are bad news!
Fuku has something to do with Oscar's love life because Fuku is a curse within his family...(I didn't get to far in the book)