Answer from cs61c-ck (Allen Lee 16583554) for Question 1
If we didn't pipeline our control, i.e. do not save the control signals into the pipeline registers between stages, we'd only have the control signals for the instruction currently being decoded.  Many many bad things can happen if we don't pipeline (save) our control signals because we might write to a register when we're not supposed to, take the wrong branch, select the wrong value to put into the ALU, etc.