If you go to the layers on the System Options that will change the template for all future projects. If you change them on the Project or Drawing Option level it will change them for that particular project or drawing. You can change them on the System Options level and then go into an existing project or drawing and "reset to system" in the layers for that respective level.
Once you have that set you can go into the modes you draw in and (like Philip says) change the visibilities for all sorts of parts of the drawing/model in each mode. Or, assign layers to be on or off in each mode. You can also select which layer is being drawn on if you do not want it on the default layer. With certain things like symbols you can assign what layer they go on in the symbol libraries. Again, you can do that in the drawing level or if you want it for all projects at the system level.
For things such cabinets, speed notes, and posts you can set a default layer within the configuration in the library menu by clicking to edit an existing or when you create a new one. With other things you can just assign which layer you are drawing on as you add pieces or entities to your drawing in whatever mode you are in. If you want a beam or some symbol to just be visible in roof mode you could use a "Roof Only" layer. There are many ways to do it. Just gotta try out what works best for you.