This research is a detailed quantum mechanical investigation of the structural, electronic, and optical characteristics of TMZnO thin films, how the dimensionality is reduced, the atoms are terminated on the surface, and the nature of intrinsic point defects. The work provides reliable benchmarks of band structures, excitonic behaviour and defect-induced electronic states using a multilevel computational method consisting of DFT (PBE), hybrid-functional HSE06, GW quasiparticle corrections and BetheSalpeter Equation (BSE) calculations. The polar and non-polar surfaces had substantial Zn-O bond-length deviations, with the interior layers having bulk-like geometry. Analysis based on thicknesses revealed that ultrathin films exhibited strong quantum confinement that led to increased band gaps and exciton binding energies, and GW gaps reaching as high as 3.8 eV in monolayers. Strong blue-shifts in the onset of absorption and greater excitonic prominence in thinner films were observed using optical spectra. Artificial defect states, especially oxygen vacancies and zinc interstitials, were found to generate significant sub-band-gap absorption as was observed in experimentally measured visible photoluminescence. In general, the results are of theoretical value in terms of their ability to understand the overall influence of confinement, surface chemistry, and defects that determine the electronic and optical activities of ZnO thin films as a valuable guideline in maximizing their functionality in nanoscale optoelectronic and photonic applications.