You are welcome, it's always good to do more research on a school you are interested in. One of the reasons I chose HLYIS because it was small and I liked the small community feel that surrounds the school.
In mandarin, the children learn Pin Yin from the start in all 3 groups. The top group (Dragon) have homework 4 times a week and it does involve a lot a writing, such as individual words as well as sentences. In P2 they have just had a small individual exam to test them on their written work as well as their reading and understanding of questions. I know the children that didn't do well in the exam, the parents were notified and there were discussions as to what options they had..eg extra tutorials or going into a lower madarin group etc. So your children doesn't just take an exam and then forgotten about, those who struggle will receive extra help.
The school does not have streaming for subjects such as Maths and English. The children however, are placed in different groups for reading according to their ability. This is great as my daughter's reading is quite advanced for her age group and when she was in P1, she was given P2 reading books to read so she was able to embrace her abilities.
I'm afraid I cannot comment on Maths for children who are more advanced as my daughter is only average in this subject but I am sure they will be given more advanced work than the rest of the class. However, I am sure the school will be able to tell you more about how they can help children who are more gifted as I know they have programs in place for children who have learning difficulties.
Let me know if youy wish to know more.