Hi Aligal,
I am a Y13 student taking Maths, Further Maths, Physics(AQA), and currently doing EPQ. I did computer science AS in Y12.
1) Obviously varies by person. The main topics common to all exam boards are(I think):
Particles and Radiation-Y12 mostly completely new concepts from GCSE, relatively easy
Waves-Y12, I found quite difficult, some GCSE content there
Mechanics and Materials-Y12, mechanics straight forward if doing A-level Maths since same content, materials is extension on GCSE content
Electricity-Y12, fairly straight forward, slight extension on GCSE content
Further mechanics and thermal physics-Y13, Further mechanics I found fairly straight forward, completely new from GCSE, though I would imagine would be a struggle if your Maths isn't strong. Thermal physics is extension of GCSE, not too bad.
Fields-Y13, by far the hardest topic I found in the A-level, GCSE barely scrapes the surface on this topic.
Nuclear physics- Extension of GCSE content, not that bad.
For AQA at least you have an option which your school picks for you, which you cover in Y13.
I personally find that physics requires the same amount of revision as Maths and Further Maths combined, but it will be different for different people. I think I have far greater aptitude in Maths then Physics. I like to make revision cards for each topic, alongside practise questions. I would say if your not planning too already to take A-level Maths, as would hugely help.
2) My school sets 2 physics homework a week which both take 2 hours. Usually just tons of old exam questions or questions on Isaac Physics or to complete the require practical write up.
3) During lesson, will have a lab partner, given some instructions for the experiment (though the amount of detail of instructions decrease as your lab skills get better), carry it out and collect data. Put the data in a table, do the write up. The write up is stating the method, variables, safety, graph, and analysis of data. There is 12 throughout the 2 years. The required practical's are a pass-fail sperate thing(though many unis would require a pass in this). The teachers just need to see that you have displayed a list of skills over the 12 practical's.
I think is very much doable. Feel free to ask any more questions.
Junias