Attaching exposure information could be useful I guess when you have it. DSLR's and hybrid cameras certainly embed it in the EXIF but of course one must rely on ones notes (or more likely, memory) when shooting film. Even digital RF's like the Leica M9 only record ISO, shutter speed and focal length, if you used a coded lens (or set it), but not aperture.
Regards shutter speed / aperture, the choice is sometimes dependent on your vision of the final shot (narrow vs wide DoF, motion blur vs absolutely static) but also the restrictions of the equipment used (sensitivity of the sensor / film, ISO selected, maximum aperture available, focal length, hand-held vs tripod). But of course it all comes down to the amount of light reflected from the subject (whether that be available at the scene or introduced by flash etc) and that will often dictate the way that you must interpret what you see.
That is the wonderful thing about photography I guess. Sometimes you need to faithfully record what you see (whether a shot of a bee in the garden or mould growth on plastic), at other times you want to capture the atmosphere or emotional impact a scene has made on you. At other times, you may have a clear vision of an image you wish to create and stage the scene to achieve this, or start to build the elements that you will use later to create it (whether in a darkroom or in the digital domain). Whatever it is, I have to say I pretty well enjoy it all (although photos of mould growing on paint can grow a bit tiring at times!!).
