Now I use for example the EF 135L at F:2.0 I can mount it to my 5D and or 60D and I get the same AE of 200/1 Second at 2.0. So the crop does not cost me any light while extending my lens to 216mm. ...Putting the lens on a crop camera extends its effective length to 216 but does not change it's front element so we have now a 1:3.456 lens (which fits to my observation with the DOF on the 5D either by rule or incident)
Putting a lens on a corp body does nothing
to the lens. A smaller sensor doesn't cahnge the focal length, that's an intrinsic property of the lens. A smaller sensor merely samples a smaller area of the image circle of the lens, meaning you get a narrower AoV from the same focal length lens.
Now to my question: How can the crop change the F number in regards to DOF but not in regards to the speed of the lens? And applied to the rest of the universe does this mean I need not only to convert the mm up but also the DOF capabilities down by 1.6 on all EF-S lenses?
Exposure (shutter speed for a given aperture) is determined by light per unit area of sensor, so a smaller sensor does not change exposure. Under the same lighting conditions, a f/2 lens on FF will give the same exposure as an f/2 lens on a PowerShot with a 4.6x crop sensor.
Practically, you multiply the aperture by 1.6x to get the equivalent DoF of a lens on a FF sensor. The underlying principle as that to get the same framing with FF, you are closer to the subject than with APS-C, and clsoer means shallower DoF. If you take a shot with the same focal length lens at the same aperture and distance on APS-C vs. FF, the DoF will actually be shallower with APS-C (because of the different circle of confusion), but of course the framing will be radically different.
The example I often use relates to people who shoot an EF-S 17-55mm f/2.8 IS on APS-C and claim they won't go FF because there's no FF equivalent to that lens. In fact, the FF equivalent to the 17-55mm is a hypothetical 27-88mm f/4.5 lens (in terms of DoF for the same framing), so the 24-105mm f/4L IS is wider, longer, gives shallower DoF, and has IS. The larger area of the FF sensor translates to 1.3-stops lower noise, which more than makes up for the stop of aperture lost in terms of shutter speed.