Answer from cs61c-ce (Aretha Samuel 15797004) for Question 1
the processor generates virtula addresses while the memory is accessed using physical addresses.  Both the virtual memory and the physical memory are broken into pages, so that a virtual page is really mapped to a physical page. The difference 
Physical addresses are provided directly by the machine.one physical address
space per machine. addresses typically range from 0 to some maximum, though
some portion if this space is used by the OS and is not available to the
procesor.

virtual address are addresses provided to the processor by the OS. addresses
typically start at zero, but not necessarily.space may consist of several
segments.