In this talk I will discuss two ongoing experiments in our lab focused on the study of cold and hot collisions in trapped gases. In the first part, I will review the mechanism of a so-called Fano-Feshbach resonance used to control collision interactions in ultra-cold gases, and I will describe how the addition of an electric field can enrich these resonances in hetero-nuclear mixtures. In the second part, I will describe a study of trapped atom loss due to collisions with a room temperature background gas. These losses, more than just a nuisance, provide a sensitive probe of the collisional physics between the target and background species and of the trap depth. I will discuss the use of such loss measurements for the accurate determination of the trap depth and the background gas density.