I'm second interested in such a knowledge. Nobody going to climb with paracord on a regular basis. But it's not impossible to descend with it, right? What would you prefer in 9-11 situation? To jump out of the window or try to carefully descend with paracord from your EDC kit even if that's not safe?

So, why don't you give us a lesson on rappelling as an expert? Or may be you know some good links on the subject? Google returns too many commercials to dig through.

What I know so far, is that for an emergency rappelling I need some sort of harness (probably ballistic nylon straps around hips and waist - the lightest variant). Rope, and a rappelling device like the figure 8 thing. Not sure about tubular devices, because they are designed for a standard rope diameters (probably the same applies to figure 8 too). And a carabiner to hook the harness to the device.

Something like this:
http://www.sealsactiongear.com/catalog/store/new_listCategoriesAndProducts.asp?idCategory=12