It's a basic tenet of Sketchup that to separate geometry you must either separately group the geometry or make it a component and then place instances of it. By default all geometry sticks together inside a model, or group or component. Hiding geometry or putting it onto layers that are switched 'off' will never separate the geometry.

Layers in Sketchup are NOT the same as layers in CAD. Layers are used to control visibility NOT geometry interaction.

Let's imagine a simple building. You'll probably want the walls on the 'WALL' layer and the roof on the 'ROOF' layer. That way you can switch off the roof and see inside the space from above...
To put things onto these layers so you can switch them on and off you should make the wall geometry with everything on Layer0 and then group the parts, make that group's layer WALL. Similarly make the roof geometry on Layer0 and group it [note how you can separate stuff early on - draw a couple of the roof's edges and group them immediately, edit that group and then everything you make inside the roof-group remains separated from the rest of the model, whilst you can still snap to any of it, drawn over it etc]. Now put the roof on layer ROOF. Now you can hide the roof or wall by simply switching off layers.

Also naming the roof-group and wall-group logically allows you to select these in the Outliner...

Putting the model's raw geometry [or basic geometry inside a group/component] will only stop it being seen - it will not stop it interacting with other things. It is usually best to have all raw faces and edges on Layer0 - keep the active_layer Layer0 [radio button], the visibility of layers is controlled by the tick-box...

Awww, I'm trying to be lazy about it. When you have ~400 components on a level, replacing all the text can be kind of a chore. I'll just plop them down after I do the mirror function.

What Miguel says...

You can always check what colours/textures your (double sided) faces have by right clicking on a face and selecting "Entity info" from the context menu. You will then get the dialog with a small thumbnail for either colour/texture.

DoubleFace.jpg
Notice that in this exmple I set the "Front face" (which is the "whitish" by default) as an opaque grey and the "Back face" (the "bluish" by default) as a 100% translucent something (in this case what the colour originally is is indifferent). Translucency is indicated by that diagonally divided rectangle of the colour sample.

@unknownuser said:

If I'm using the program wrong, so be it. It doesn't seem to damage my workflow at all.

If you have a settled workflow and able to follow it without any problems, no-one can say "you are using the program wrong". What we mean here (and especially in the "Newbie department") is that if someone has no experience or a well founded workflow, (s)he shouldn't switch between layers without really knowing what (s)he does.

@unknownuser said:

The only real problem is that I can't make a component that can "cut" across multiple components or layers of geometry, and have to rely on intersections and clean-up. That's just a limitation of Sketchup and not layer related.

That's true - it has nothing to do with layers but components which separate geometry and prevent things from interacting and affecting each other. But never mind; components cannot cut through thick walls anyway so once someone models with double faced walls, needs to intersect things (or use other tricks) anyway.

Hi Halkun (and welcome).

The method you are doing is the way it should be done in (native = no plugin) sketchup. One thing you need to know however is that

intersection lines will always appear in the context you are in at the moment of performing the action (i.e. in your case, outside of either component) this also means that you can only perform a boolean intersection if the two shapes are within the same context (i.e. in your case they are not two, separate components)
Well, that was two, not one, but the solution is: after placing both components and the other geometry, explode everything, do the intersection and delete unwanted geometry.

There is also a fine "BoolTools" plugin should you need this operation very frequently and especially hate deleting unwanted stuff. It's $ 10 however - but that's only a snack at McDonalds...

It works with separate groups (and end up with one, "joint" group)

Yesterday I have seen new Star Trek, it is great and Your model is perfect, thank You !