Well, you're definitely going to want to take that Physics class senior year once you have the chance, and see how well you do in it, and whether or not you like it.
The worst case scenario for taking it is that you fail and realize that physics isn't a good idea for you, which isn't as bad as not finding that out until you go to college.
Your grades aren't good, so I would try to improve those.
There are a lot of different ways to study for math, but the best advice that I've ever gotten was to always look at the history of whatever I'm learning about.
I have the sort of brain that refuses to accept anything it doesn't understand.
When you look at the proof for whatever theorem you're using, and you understand the thought process that whoever invented it was following, you can get a much better feel for what everything actually is.
If you can understand what and why you're doing everything that you're doing, then solving problems comes much more easily.