The EVFs are showing what is in essence the out-of-camera JPEG, with about 1 stop clipped from each end. And as we all know, the out-of-camera JPEG contains several stops less DR than is available in the raw data.
Interesting. So the camera is essentially generating 60 or more JPEG images per second, plus adding overlay data to it. Amazing.
Not even close, at least on Canon P&S cameras.
For live view (either on the LCD, or EVF), the sensor image is converted to an 8 bit, 4:1:1 YUV image.
This has a luminance (Y) resolution of 720 x 240 pixels on most Canon cameras; but only 180 x 240 resolution for each of the chrominance channels (U & V).
Some cameras, such as the G12 & G1X, double the vertical resolution to 480 lines.
My understanding is this is done using a special read-out mode on the sensor; but I may be wrong there.
The live view is normally done at 30 frames per second, except in low light when the camera will lower the refresh rate to capture more light per frame.
There is no JPEG processing being done.
Obviously there's no JPEG encoding as that would be pointless, but some processing is done because you can change it by changing things like contrast and saturation. Further, I measured my SX50's lag by shooting 240fps video of both its output and of what it was looking at at the same time and I got right at 25ms in good light. I don't see how this is possible if it's running at 30fps.