I'm going to take your last question first. Our specialty is the GMAT itself, not the admissions process—and the admissions process takes into account much more than your GMAT score. I recommend talking to some admissions consultants re: that topic. From what I do know, top-10 schools are a stretch with a 660, but you should be okay with some schools in the top 40 (based on the GMAT alone—the rest of your profile will matter too).
You can go onto the school websites and look up their posted statistics—they'll typically say what their average GMAT score is, along with the range of scores from the people accepted into their program (usually, they'll post the "middle 80%" range).
By the way, you do
not need to score 720 to go to a top-40 school. So unless you do want to go to a top-10 school, you might be able to lower your goal score.
Next, good job on getting yourself to 660! I know you want an even higher score, but a 660 is a very good score, too.
Your quant score is almost at the top—the highest score is 51. There is more room for growth on the verbal side—but that side is also your weaker area. So if you would still like to aim for 720, then I would advise that you continue to study some quant in an effort to try to get yourself to Quant 51 (our Advanced Quant strategy guide might help you with that).
If you can get yourself to Q51, then you would need to lift verbal to about 37, or 7 points higher than your current score of V30. If your quant stays at 49, then verbal would have to be about 39 or 40.
How have you studied so far? What materials have you used? Whatever you have been doing on the quant side, you can probably continue to use a similar process to lift another point or two. On the verbal side, you may need to try something different, as you need to see a larger increase there to hit 720.
If you have been self-studying, you may want to take a class (or go straight to a tutor, since you need only very targeted help on quant). If you have taken a class, you may want to work with a tutor (try to find someone who is especially skilled at teaching verbal—a larger proportion of tutors are great at teaching quant but not as good at teaching verbal).
Let me know how you've been studying so far and we can discuss further!