When you do a HDR RAW it packs the three files into one file and you can later extract them in the Pentax software. No difference to doing a bracketing BUT if you develop in camera you will get a finished HDR. Also you can shoot RAW+ to get the jpg directly. No software sees the HDR RAW as HDR, not even Pentax. It will show you one of the packed files.
Highlight and shadow does what is says, lower the highlights and opens up the shadows. If you shoot RAW and use Pentax software it will be applied in the software but if using Adobe it will not have any impact.
The HighISO I always have turned off.
The ISO at slow shutter speed kicks in when slower than 30 seconds and gives you a dark frame subtraction. Meaning if you shoot for 60 secs it will do a dark frame for 60 more seconds to remove sensor errors.
Hold AF. Look at the film they have at the Pentax site. It will hold the focus if something closer to you gets in the way of your subject, a person or a tree or...
---------- Post added 10-11-14 at 06:45 PM ----------
There is a book by someone, I do not remember, but search the forum for "K3 manual Sucks"...
---------- Post added 10-11-14 at 06:47 PM ----------
Found it:
https://www.pentaxforums.com/forums/172-pentax-k-3/246364-yvons-k-3-book-available.html