Interactions between galaxies and their larger scale environment is a central tenet of structure formation theory. However, this idea encompasses a long list of processes. Indeed, galaxies grow from intense gas inflows at high-redshift and acquire spin through tidal torques on larger scales while merging with one another at the same time. None of these processes is independent from the large scale distribution of matter, strikingly anisotropic and consisting of an extended network of voids delimited by sheets, themselves segmented by high-density filaments within which matter flows towards compact nodes where they intersect. Such a structure imprints its geometry on cosmic flows, especially gas inflows and drifting galaxies, ultimately shaping the distribution of galactic properties.This work investigates some of these correlations between galactic and extra-galactic scales in the hydrodynamical cosmological simulation Horizon-AGN. First, I analyze and quantify the spin orientations of galaxies and show that both minor and major mergers can drive important spin swings. I further investigate the distribution of satellite galaxies around a more massive host and find it to be also fairly correlated to the direction of the surrounding filament. However, this trend is in competition with a tendency for satellites to align their orbits in the central galactic plane especially in the inner parts of the halo.Finally, I study the impact of mergers and diffuse accretion on the size and shape of galaxies at the peak of cosmic star formation history. The main results statistically support the gas-poor minor merger scenario to interpret the loss of compacity of spheroids at low-z.