Precise control over interactions and measurements in quantum systems is crucial for applications ranging from simulating collective many-body dynamics to enabling fault-tolerant quantum computation. In this talk, I will highlight our work in realizing nondestructive readout and long-range interactions in atomic tweezer arrays using a strongly coupled optical cavity. The cavity photons serve dual roles: they efficiently transfer quantum information from the atomic system to external measurement devices and act as force carriers, facilitating long-range interactions among the atoms. By selectively coupling a single atom to the cavity mode, we achieve rapid mid-circuit measurements without perturbing the quantum coherence of the other atoms—a crucial step toward quantum error correction. Conversely, the collective emission from multiple atoms into the cavity can be coherently enhanced or suppressed. We demonstrate atom-by-atom control over collective atom-light interactions, observing both super- and sub-radiant cavity emissions from the constructed atomic ensembles. Finally, This collective atom-cavity coupling sets the stage for engineering long-range interactions through photon exchange, enabling the observation of self-organization phase transitions in mesoscopic systems and revealing key hallmarks of mesoscopic physics.