Answer from cs61c-cl (Hiroki Terashima 16032281) for Question 2
Statements that are involved in making decisions:
if, else if
while
for
do...while
(...) ? ... : ...
switch
goto

for MIPS:
beq
bne
loop
slt

I think the designers wanted to keep things simple so that the code will run faster.  Statements like do...while and for are "extras"- they can be written using the statements we already have, so why use them if it's going to slow down the processing time?