We held a birthday party at the ballroom of HK Disneyland Hotel in Nov 2005. The food and service were good. The charge per person for food & beverage plus ticket was about HK$1,200.
For 30-40 persons, you can get a function room. I contacted the banquet dept last year for company activity. The staff was nice. You can always call to get information.
Only 7 classmates / friends and their family members / maids came. I believe the venue is too far. We live in Shatin. Most of the guests were our family members and friends.