My family moved to HK a few months ago from USA and both my girls (age 10 and 7) go to HLYIS, which we all love! We had places at ESF and AIS, but we all just fell in love with the small suburban feel of HLYIS. I was worried about the transition, as both girls had loads of school friends in USA, but the staff at the school and all the students there made my girls feel at home right away. Can not recommend it highly enough.
As for where to stay, I agree that you should come to HK and visit different areas to see for yourself which area you prefer to live in. We live in Beverly Hills and love it here. A little fancy and pretentious on the outside, but pretty down to earth on the inside. The facilities here are 1st rate and the management constantly maintains them to a high standard. I viewed loads of houses and apartments from Shatin to Taipo as well as Hong Lok Yuen and just liked the atmosphere around here, good bike trails and lots of open green space. In fact, we did not even know about the HLYIS when we came to HK--and only saw the school when we viewed some houses in the community. The houses that were available for rent at HLY were pretty nasty, at least when we were house hunting. I am sure that there are lots of nice houses there, but the only ones for rent when we looked were real run down and not suitable for us.
I would recommend staying at the Hyatt at the University in one of their long units for about 1 month and shop for houses.
It takes about 45 minutes to get to HK Island by car by the eastern harbor tunnel and there is the 307 bus that goes from TaiPo center to HK Island, about 1 hour. Again, this might be a terrible commute for someone and might be an easy commute for someone else, it depends what you are used to back home.
If you need more info, please feel free to PM me. I used a real good local real estate agent and we got a smoking deal here in Beverly Hills, the lowest rent per square foot for sure. Just for your info, there is a school bus that takes our kids from BH to HLYIS, pretty convenient!
Best of Luck!