I will discuss recent results from the “Keck Baryonic Structure Survey”, a unique survey of the high redshift universe optimized for sensitivity to both forming galaxies and the surrounding gas-phase circumgalactic and intergalactic baryons (and the exchange between the two) at 2 < z < 3, when the relevant energetic processes (star formation, black hole accretion) were at their historical peak. I will emphasize how “wholesale” near-IR (rest-frame optical) spectroscopy of distant galaxies, made possible by the recent commissioning of MOSFIRE at Keck, vastly improves measurements of metallicity, kinematics, and physical conditions—both inside galaxy HII regions and in the CGM/IGM.