alpha/depth: yep you click on the colored/alpha or depth image and then choose save. alpha ground plane: just pick render selected objects, that will remove everything that you havent selected including the groundplane from the alpha version but keep the groundplane when rendering so you get the correct ligtning. You can also put the stuff you want to render in a layer on its own and pick render active or visible layers. cameras: you can create more cameras, check the manage camera options.