Welcome to the forum izzytr
The books seem to be of little real benefit in TS4. It's easier and way quicker to skill up doing the actions rather than reading and as far as I know the only way to tell if a sim has read a book is to click on it and see if the descriptor is 'reread'.
Fiction just seems to be either for fun or for manipulating sims emotions, however there are quicker ways to get your sim flirty (for example) than reading a book.