Artificially layered materials are ideal model systems to tune the dimensionality of the superconducting order as well as the structure of the flux line lattice. Our extensive studies of Pb/Ge multilayers indicate that the anisotropy of the upper critical field H_c2 strongly depends on the Ge separator thickness d_Ge. The dimensional crossover from D = 3 towards D = 2, which is revealed by an upturn in the temperature dependence of the parallel critical field H_c2^||, is also confirmed by the observed excess fluctuation conductivity above T_c. In samples for which D = 2 at all temperatures (d_Ge > 50 Å), the structure of the flux line lattice for a perpendicular field H_⊥ can be probed by measuring the critical current density J_c. The variation of J_c(H_⊥) exhibits an anomalous minimum, whose amplitude and position depend on d_Ge, the number of bilayers, temperature, and pinning strength. An interpretation in terms of either fluxlattice decoupling or melting is presented.