1. What is the temperature dependence of the magnetic susceptibility of a Pauli paramagnet ?

It is temperature independent.

2. How is the measurement of Hall effect performed?
    What important information can Hall effect measurement give?

In a Hall effect experiment a current is passed through a plate-like sample in the plane of the plate (call this the x-direction). A magnetic filed is applied perpendicular to the plate (call this the z-direction). As a result a potential (Hall voltage) is developed along the y-direction. The Hall effect experiment gives information about the density and sign of charge carriers.