i got BBC last yeaar like you, A in math and psychology. Narrowly missed A* and got some perfect marks for some papers but messed up others so overall A in math. I screwed up physics resit.
1) Originally just procrastinated and whenever i felt like it, but later, i used 1focus to block distracting apps, stayfocusd to block distracting websites, and that allowed me to put more effort in studying. I used Pomodoro Method although 17 minutes was often too long, but sometimes too short. You need to be ablle to do several hours a day every day to keep up.
2) Isaac physics for physics and math, PMT, examsolution for math, birmingham uni practical resources for physics practicals, some cambridge supercurriculars to expand my understanding of math and physics, a level physics online for physics, even bits of other stuff like openstax textbooks, mit open courseware, principles of physics by resnick Halliday (not too useful, except the mechanics and for further understanding), math methods book for physics and engineering by riley hobson bence (only some parts useful, just for the physical meaning etc.), byjus for math, drfrostmath seneca underground math madas math isaac physics books and so many things, even a bit of university analysis for proofs. A lot of stuff.
3) Depends. winter 2022 it was 1-2 hrs then increased 2-3, 3-4, 4-5, finally 6hrs and my best for 2022-23 was 9 hours. For 2022 i also did gcses as well and sometimes studied basically all day, even replaying past paper videos from my phone to remember the content (only partially worked). It was stressful to say the least.
4) i suppose the hodder education aim for A in physics works, as well as chemistry. more isaac physics, more exam questions for math, i suppose.
5) use exampro as someone suggest, don't do same past papers as it can trick you into thinking you're doing better. i dropped from A* predict in physics to B in 2022 because of that. And in Math to some extent. Psychology a little. Either way, keep practicing. For resits, better use a college to help you.
So if you resit Math and physics, get your scripts, see where you are quite weak at, and improve them. Hopefully you at least get AAB or even A*AB and A*A*B.