Family 3day tour wud be visiting TST, Disneylad, Peak, etc which card is suggested for trael in MTR?

Am travelling to HK with my family (2+2) and would like to know:
Which card would be ideal to travel to
A) Airport to TST,
B) tst to Central, Peak, Tram, Disneyland?
My travel is through MTR/bus only. Airport Exp card? or Octupus card is suggested?

2) Is one card for all or separate card for an individual or kids?
3) is deposit refunded immediately upon return of card?

Wud be highly obliged if you could reply my queries at the earliest?