Answer from cs61c-au (Robert Webb 14343043) for Question 2
All programs would have to be coded into a single file, which is impractical given the size of most programs.  Also if a single program instruction is changed, the entire program would have to be compiled, assembled, and linked again.  With the current model, only the modified portion would need to be compiled and assembled, it would then be linked to the rest of the program.