My family will visit Hong Kong this coming Nov from 21 until 26.

Well, it is hard to predict the accurate weather at those days, but according to the weather records, it was usually sunny, cool, and rained little at that time, the average may reach 70F. You need to wear long-sleeve t-shirt and thin coat. Typhoon seldom occurs at that month, so you do not need to worry about it.
During your stay, you can visit the Disneyland, Ocean Park, Victoria Peak and Ngong Ping 360.