Lamellar phases obtained by mixing water and oil with intervening surfactant monolayer interfaces (eventually containing low molecular weights amphiphilic block-copolymers) are studied. Structural and dynamical investigations of oriented lamellar phases at the length scale of the intermembrane distance and beyond are performed using Small-Angle Neutrons Scattering (SANS) and Neutron Spin-Echo (NSE). The data analysis in terms of static and dynamic structure factors for a stack of elastic interfacial membranes yields information of the membrane curvature elasticity and membrane interactions in terms of membrane properties. The conditions of applicability of the available theoretical concepts to extract, e.g. the bending modulus from NSE data, are discussed.