You have to ride it for a while first before you feel comfortable about 'taking it apart'. Just a thought for you there.
Channels serve a couple of specific purposes.
Ones that you can't use will be dimmed out in the menus. Alpha channels are not part of your image's colour composition, and have no effect on that directly. They are explicitly 256 grayscale in colour. You can apply most of Photoshop's native filters to them to create complex and interesting types of selections. Channels are also used as Texture Channels within the Lighting Effects filter, to create a minimal type of 3D effect on a coloured area of a layer, or a specific selected area of an object on a layer.