Answer from cs61c-cj (Peter Lau 16539384) for Question 2
The compiler in this case would be hardware specific.  Since the C program gets directly converted to a machine program, the programmer would have to use something else if he or she wanted code to be converted to something else that the combined compiler could not do.  A combined compiler might post an optimization problem since it skips the assembly stage, in which an assembly expert could possibly optimize the code.