My daughter is studying P1. So far the homework has been OK, less than we expected before attending. She should have enough playtime (with her classmates and friends) especially weekends. I heard that more homework since P4 but I'm not sure.
My daughter is happily going to school. Usually it has 3 times Chinese and 2 times English dictation per month. As a P1 parent's opinion, the school is not as hard as what said outside.
No need to worry. The school has "adaptive period" for students transit from Kindergarten to Primary. I believe most schools have the similar arrangement.
Yes, at least one music instrument is required. Piano is OK. And again, no worry, the school has after-school class for different instruments, you can also consider learning them.