In-situ recording of ultra-thin film growth by Low Energy Electron Microscopy (LEEM) results in accurate determinations of monolayer metal deposition rates for difficult to calibrate deposition geometries. Deposition rates and growth features were determined for Cu and Co on W (110) allowing for thickness control at the submonolayer level. Also, the transparencies of non-Magnetic overlayers of Pd (111) and Cu (111) to very low energy spin polarized electrons were compared and qualitatively explained by band structure considerations. Cu (111) is much more transparent than Pd (111) so that magnetic domain structures can be observed through at least 4 nmof Cu (111). This suggests the use of Cu (111) and other metals of suitable band structure as protective layers for surface magnetic studies.