ENGAA / Engineering at Cambridge

I believe that the ENGAA is changing from next year, yes. Also, for the second question, it should be only things from the first year of the A Level physics and maths syllabus. There is a specification online, if you search ENGAA specification, that tells you everything that you need to know. Some content is not covered in some courses, so you might have to teach yourself a couple of things at most, but everything else should be fine. For example I've had to teach myself about youngs modulus since I study the IB and it's not in my course.
For the ENGAA, I think its less about learning the content anyway and more about being quick at solving the questions - the time pressure is probably the hardest part in my opinion, the questions aren't too difficult but you have to do them insanely quickly