Answer from cs61c-en (Lai, Siu Lun Chris 16529329) for Question 1
No, we don't need them all
do while and goto can be dropped.

The reason why the designers include them all is that sometimes it maybe easier to write the program in do while or goto. For example, if we want to enter the loop at least once, we write do while; if we want the control to go a certain point, we may want to use goto, although it is rarely used.