Colour Management in a bit more depth.

This is the presentation about Colour Management.

I have the following advice.
If what you do works, then do not change it.
If you are just starting out then use sRGB throughout. You will never notice the difference and usually you are working in a single stimulus situation.
If you decide to play take screenshots of what your current settings are, so you can go back if things go wrong.

The presentation contains three movies which can be played. These should help you to understand the fact that colourspaces are different shapes.
The first is sRGB rotating in L,a,b colourspace.
The second is a Printer/Paper profile and shows the gamut of that Printer/Paper (Epson 3800/Premium Semigloss Photo Paper)
The third shows Adobe RGB as the solid shape and the above Printer/Paper combination as a wire frame. It can be seen that the printer is capable of printing colours that are outside the gamut of Adobe RGB. Those are the colours where the wireframe shows.