What are my chances of getting into this college...?

Honestly, B's probably won't cut it. One or two here and there won't ruin your chances, but Cornell is a very competitive school. Take the most challenging cles your high schools offers, but get A's--high A's to be exact. Practice for your SATs and score at least a 2000 (I'd say a 2100+ is pretty solid for Cornell). Keep in mind, though, that the SAT is merely one part of the admission process; colleges do not weight entirely on one test from a Saturday morning--reiterating on keeping your GPA high. Get involved in EC's... it appears as though you already are, but make sure you commit to them and participate in a lot of community service. Finally, when you actually do write your essay(s) for your application, make sure it is flawless. Make yourself stand out from every other applicant, be "unique." It is definitely not the hardest Ivy League to get into, but then again, it's an Ivy League so it is very selective. And to be honest, you will probably change your mind about college numerous times... there are many outstanding schools out there that aren't Ivy League. I really hope you have visited Cornell, because if you haven't it may turn out that you hate it. Best of luck in your future.