Answer from cs61c-er (Chienyu CHIEN 17789156) for Question 2
Call self function will be eliminated.

if A pass a argument of 3, placing the value 3 into rigister $a0 and using "jal" A. then if procedure A calls Procedure B via "jal" B with argument of 7,also placing into $a0. But A procedure have not done it's work yet, there will be a conflict over the use of register $a0.