Some US med students use Kaplan. It all depends what works best for you. Kaplan is pretty dense, takes alot of time.

Step 2 is all about what you hopefully learned in clinicals and bringing it together with basic sciences as your foundation. It's really all about you and how much you read on your own or tried to learn from your preceptors or did you just showed up to clinicals to get an eval good enough to pass the rotation. Step exams for clinicals would force those without "desire" to read during rotations to do so, AUA doesn't have Shelf exams for clinicals . US med schools don't prep you for Step 2 really, it's not on them, but they do have shelfs which is something AUA might want to consider in the future.

Step 3 is again all on your own. Most people take it after their intern year.