We study the finite temperature phases and collective excitations of hardcore as well as softcore bosons on a square lattice with nearest and next nearest neighbour interactions. We focus on the formation of various types of supersolid phases and their stability under thermal fluctuations. Interplay between the on-site, nearest and next nearest neighbour interactions lead to various density ordering and structural transitions, which are charted out. Thermodynamic properties and phase diagrams are obtained by extending the cluster mean field theory at finite temperatures which includes quantum effects systematically. We investigate the melting process of supersolid phase to normal fluid, which occurs in two steps due to the presence of two competing orders in the supersolid. The existence of a tetra-critical point at finite temperature exhibits intriguing behavior, which is analyzed for different regimes of interactions. We show how the phases and the transitions between them both at zero and finite temperatures can be identified from the excitation spectrum. Apart from the gapless sound mode, the appearance of Higgs like gapped mode in the supersolid phase is analyzed, which is a characteristic feature of such phase. Finally, we discuss the relevance of the results of the present work in the context of ongoing experiments on ultracold atomic gases and newly observed supersolid phases.