We investigate the fusion barriers for reactions involving Ca isotopes Ca-40 + Ca-40, Ca-40 + Ca-48, and Ca-48 + Ca-48 using the microscopic time-dependent Hartree-Fock (TDHF) theory coupled with a density constraint. In this formalism the fusion barriers are directly obtained from TDHF dynamics. We also study the excitation of the preequilibrium GDR for the Ca-40 + Ca-48 system and the associated gamma-ray emission spectrum. Fusion cross sections are calculated using the incoming-wave boundary condition approach. We examine the dependence of fusion barriers on collision energy as well as on the different parametrizations of the Skyrme interaction.