Cold gas plays a central role in feeding and regulating star formation and growth of supermassive black holes (SMBH) in galaxy nuclei. Particularly powerful activity occurs when interactions of gas-rich galaxies funnel large amounts of gas and dust into nuclei of luminous and ultra luminous infrared galaxies (LIRGs/ULIRGs). Dusty, luminous galaxies are of key importance to galaxy mass assembly over cosmic time. The most active growth spurt is suspected to occur when the SMBH is deeply embedded in a dense, dusty ISM. Obscured AGNs can ultimately provide fundamental constraints on the AGN duty cycle, give the full range of environments and astrophysical processes that drive the growth of SMBHs, and help to complete the picture of connections between the host galaxy and SMBH. Understanding the molecular properties of local U/LIRGS and AGNs thus is essential both for defining the evolution of present day galaxies - and sorting out key astrophysical processes in their even more energetic, distant cousins and intermediate to high redshifts. It is also increasingly clear that feedback from star formation and AGNs is fundamental to regulating the evolution of galaxies in the nearby Universe as well as at earlier epochs. There is mounting evidence that massive amount of cold molecular gas is being expelled from galaxy nuclei and starburst regions by the feedback process. With the advent of ALMA and the NOEMA telescopes we can now study these outflows at unprecedented sensitivity and resolution. I will focus on recent ALMA and NOEMA studies of nearby enshrouded nuclei and AGN and their feedback. Recent ALMA studies (with resolutions of 20 milli arcseconds (1 – 7 pc) , reveal launch regions of molecular outflows and jets, inflows, and dusty nuclei of the nearby AGNs and LIRGs NGC1068, NGC1377 and IC860. The outflows are different from each other where NGC1068 shows gas carried out by a radio jet, NGC1377 has a 150 pc scale radio-quiet molecular jet, and the IC860 flow is exceedingly compact and dense and appears to be young. I will also discuss observational methods that reach behind the curtain of dust in the most obscured centres of U/LIRGs , allowing us to undertake new studies of heretofore hidden, rapid evolutionary phases of galaxy nuclei.