S is for changing gears at higher RPM's. When you floor it you get quicker acceleration as well. Shift the shifter into S when you have an open road in front of you and your speed is above 80 Km/h.
B is for uphill climb or high altitude terrains. It remains in one gear in order to get the most traction on the wheels possible.
No, the Super CVT-i has a P, R, N, D - S, B gear shifter pattern. The 4WD variant has a 4-speed ECT transmission with the gate shifter option which is completely different as compared to the Super CVT-i.