1) This is more of a research question than anything, Euler's number is one e = 2.718...there is also the lower case Greek letter Phi which is debated to be given as the golden ratio phi = 1.618... there is also the coefficients of static and kinetic friction, both denoted by the Greek letter mu with lower case subscripts of s and k respectively. The decibel (dB) is a pure number. Radians are dimensionless as well
2) The units of volume are cubic meters if SI units are being considered. The reason that the volume of that cylinder would not be right is because the units would be meters to the fourth power. The equation for the volume of a cylinder is (pi) r^2 h, which would give an answer in meters cubed.
3) The displacement is a vector quantity which means that when the bicyclist travels from north to south end on the circular track they travel twice the radius which is the diameter of the circle. One complete circle around the track would yield a displacement of 0 meters.
