One tip for C4D is to right-click on any item in a window and choose "Show Help." This will open the help doc and scroll to that specific command.
In most cases, you'll want to choose Straight Alpha. Something about avoiding darker edges when you composite. The Compositing Project can be handy if you have many multi-pass layers in your render. For example, if you go to the detail of using a separate pass for shadows, highlights, reflections, etc., and you choose After Effects for example, when you import it into your project, it will make a comp with all your layers stacked with the appropriate layer mode set already. Just saves time so you don't have to drag them all in and figure out what mode to use.
