QUESTION: 
Is the rover going to return to the landing craft or will it stay where it
is when mission is complete? What happens to the rover after the 30 sol
primary mission of the lander?

ANSWER from David Dubov:
After the 30 sol primary mission, if Sojourner is still functional, it will
be directed to explore beyond the range of the imaging system on the lander
(about 10 meters), and possibly beyond the range of the communication system
(about 500 meters).  This is known as the "extended mission".  It will be
asked to image the terrain, take measurements with the Alpha Proton X-ray
Spectrometer of soil and rocks, and take engineering measurements.  At the
end of a sequence of commands, the rover is directed to drive back in the
direction of the lander.