Some notes to issues touched above.
1. Careful with interpreting the in-camera histogram. As long as it is not purely raw-based, the histogram even with neutralised WB and other settings will not even resemble the raw histogram for following reasons:
b. color space conversion from camera to sRGB or whatever
These steps mix the raw channels into the RGB channels.
c. non-linear encoding ("gamma"). This step causes the distribution to be "compressed".
The effects of a. and b. are not very bad, except for very special illumination.
The effect of c. is very large; see the different histograms below from three images with different exposures: one is the raw, then the linear luminance displayed by Canon's DPP, and the RGB, again by DPP.
Consequently, the amount
of clipping or close to clipping can not be judged from the in-camera histogram, but the indication, that probably clipping occured is reliable - and that's the point. If the camera displays clipping on the LCD (I guess this is the norm these days), that is more reliable.
I have been using the neutral setting for months, and I am absolutely satisfied; the clipping indication (blinking on the LCD) matches exactly with that based on the raw analysis (as far as it is discernable on the LCD). However, apparent "underexposure" (from the perfect ETTR) is much more, than the histogram indicates.
2. The automatic exposure adjustment is recorded in the tag BaselineExposure. It can be seen only in DNG format. The adjustment is not visible on the slider.
3. Images from the Canon 1DsMkIII will be automatic adjusted by +0.35 EV.
Note, that not only the exposure, but noise reduction and sharpening too are recorded in DNG format (BaselineNoise and BaselineSharpness). I really do not know, how far these affect the ACR processing, but I guess they do. In other words, the noise reduction is unavoidable. Furthermore, I don't know, if this noise reduction and the one specified are additive. Plus, this specification does not distinguish between luminance and chrominance NR.
4. The "recovery" slider appears to have nothing to do with true recovery of clipping; that is apparently automatic. It works well on uniform or quasy-uniform areas, for example on skies, but not on very fine details - this is understandable.
5. *All* TIFF tags can be extracted by http://www.cryptobola.com/PhotoBola/free/RawnalyzeTL.exe
This program creates a text file named "original file name.taglist.txt" in the same folder as the input was. It can be used on any TIFF. When started in Windows, it will stop running after having created the text file. It can be started from command line as well (one can specify a function for example "Taglist" in Windows Explorer, and create the tag list by right-clicking on the file name). If someone wants to do that, I post the details.