I got an A* at GCSE and got an A in maths and a B in further maths last year for AS.
I have found a lot more revision is needed for AS and A2 than GCSE. For the GCSE exam I only revised for 2 days before, while for AS I worked from the Easter holidays.
For A2 I'm predicted an A in maths but I would like to get an A*, and in further maths predicted a B.
How many hours a day is just how many I feel like, can range from like 0-7.
Basically a lot more work is required than GCSE so I wouldn't say it's easy, but it's fine as long as you put in the effort.