PSCS5 uses a different termonology. Perhaps you could think of "projects" as combining "layers" for your purposes. You can open multipal images in PS and drag them into layers of one main image. CS5 dose not use theme presets like Elements does. Elements is a combination browser, editor, project starter. It's a package. PS is a component module, along with Bridge, Lightroom etc. CS5 does not use a project bin.
Images in CS5 are generally opend through Adobe Bridge which you probably have. With Bridge, you can choose multipal images you want and open them in Photoshop then combine them any way you want in layers, resizing them to any size you want. Or you can use or create presets to automate the process. Knowledge of PSCS5 is easily available on the internet. You can search and ask any question on Google, watch videos, listen to podcasts, and get an answer.
