I have the K20 and I do really like it. I am still learning and my skills are still increasing. I have not out grown it yet, and since I just had it repaired (lots of noise on the bracketing shots - new main circuit board and sensor), while still having about another 18 months left on the extended warranty Pentax provided, I fell no rush to move on to the K5.
I have found that if you have the wired shutter release connected, even if the camera is turned off, it will take the image(s - if in bracketing). Also, I believe if you depress the OK button and turn the wheel, you can adjust the ISO.
And - if in green mode, no bracketing. You have to be in one of the other user modes P, AV, etc.....