1) I started properly in January and achieved AABB!
2) They worked for me, but if you don't feel they work then ignore them and find something that does!
3) There is a lot of work involved so it always helps to enjoy the subject, but it isn't the end of the world if you don't.
4) GCSE to AS is pretty huge, there's a lot more independent work and teachers expect you to be more responsible for your own education.
5) They will to start with but your progress and achievements throughout the year are more important.
6) I didn't take any sciences, unless you count Psychology, but friends have told me that the amount you need to know for the sciences is incredibly difficult... there's a lot to learn!
Good luck with this year, its really not as bad as it seems as long as you put in the work!