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)parallel-to, is also confirmed by the observed excess fluctuation conductivity above T(c). In samples for which D = 2 at all temperatures (d(Ge) > 50 angstrom), the structure of the flux line lattice for a perpendicular field H(perpendicular-to), can be probed by measuring the critical current density J(c). The variation of J(c)(H(perpendicular-to) 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 flux-lattice decoupling or melting is presented.