1. There is no class named Predicate. There is just an interface named
Predicate. Just near the begining of section 12.5.3, the book says, "Filtering through a list of objects is such a common requirement in Java application that the Java standard library includes a generic interface for this purpose - java.util.function.Predicate.".
2. Yes, you can use a Predicate object in the CarMall example. Not sure if you have gone through Section 12.5.3 carefully but it explains exactly the question that you have asked here. It shows exactly how you can replace CarFilter of CarMall example with a Predicate.
3. OCAJP exam requires you to know only the Predicate interface and its usage with ArrayList. The book discusses all that you need to know about this for the exam in Section 12.5.3 and 12.5.4. So, go through these two sections very carefully.