Answer from cs61c-ao (Roger Tseng 16507336) for Question 2
this won't run at full speed because the second instruction depends on the first instruction.  therefore, the second instruction must wait for the lw before it can get the value of $t0 therefore causing a stall in the pipeline. the solution to this is called forwarding where you get the needed value as soon as it becomes available.  this however, still does not prevent stalls because you might still need to stall a pipeline while waiting for a value.