Basically I think the most difficult part for parents to comprehend is how teachers assess interview performance.
It's often heard from parents that the belief is the display of existing ability of a child during interview (e.g. the correctness of their answers). However, for a competitive school, what they are looking for is the potential to learn and even excel. A simple display of what they are capable of doing now is not an ideal indicator of their potential. This is where the difference is.
Definitely not. My friend's daughter has the 2nd interview at DGJS. Both of her parents are not professionals, not businesspersons. Family monthly income is around 60K (4 family members and one helper). They just rent a flat in the New Territories.