The specific color selector allows you to choose specific colours within a color space.
Fairly straightforward. This color space chooser allows you to pick the color space, the bit depth and the icc profile in which you are going to pick your color. Use the checkbox 'show color space selector' to hide this feature.
These change per color space. If you chose 16bit float or 32 bit float, these will go from 0 to 1.0, with the decimals deciding the the difference between colors.
This is only available for the color spaces with a depth of 8 bit. This allows you to input hex color codes, and receive the RGB, CMYK, LAB, XYZ or YCrCb equivelant, and the other way around!.