  Galaxy evolution and star formation are two multi-scale problems tightly
linked to each other. To understand the interstellar cycle, which triggers
galaxy evolution, it is necessary to describe simultaneously the large-scale
evolution widely induced by the feedback processes and the details of the gas
dynamics that controls the star formation process through gravitational
collapse. We perform a set of three-dimensional high-resolution numerical
simulations of a turbulent, self-gravitating and magnetized interstellar medium
within a $1\ \mathrm{kpc}$ stratified box with supernova feedback correlated
with star-forming regions. In particular, we focus on the role played by the
magnetic field and the feedback on the galactic vertical structure, the star
formation rate (SFR) and the flow dynamics. For this purpose we vary their
respective intensities. We extract properties of the dense clouds arising from
the turbulent motions and compute power spectra of various quantities. Using a
distribution of supernovae sufficiently correlated with the dense gas, we find
that supernova explosions can reproduce the observed SFR, particularly if the
magnetic field is on the order of a few $\mu G$. The vertical structure, which
results from a dynamical and an energy equilibrium is well reproduced by a
simple analytical model, which allows us to estimate the coupling between the
gas and the supernovae. We found the coupling to be rather low and on the order
of 1.5$\%$. Strong magnetic fields may help to increase this coupling by a
factor of about 2-3. To characterize the flow we compute the power spectra of
various quantities in 3D but also in 2D in order to account for the
stratification of the galactic disc.
