1) when practicing with this system, I;ve felt similar to you on going over everything consciously. I don't know if you learned about this, but I've found skittering to be very useful. I've only been using the system for about a month, but what tends to work for me is skittering through the whole book. After that if I really need to, rapid reading is pretty quik becuase I'm familiar with the book.
2) To achieve spontaneous activation you only need to preview photoread and mind probe. Doing this opens your mind up to the book and puts the information into your inner mind. Activation is not needed because activation is manual and not spontaneous.
3) I photoread the harry potter book without previewing or doing anything and then just went straight into it the next day reading it like usual. I noticed that things were more visual and even when I wasn't reading I sometimes had visions from the book. This occurred especially during my dreams at night. I had intense harry potter dreams for days. So i think that photoreading does help and benefit regular reading.
4) I think that having a specific purpose is beneficial. Instead of saying that "i want to know the information in this book to pass a test", instead say that "I want to have a strong understanding of the book so that I can consciously recall information when needed." I also think it helps to add in how you want the book to affect your life. So as a purpse for the photoreading book-
"I am reading this in order to learn the concepts of photoreading so that I can use them in my everyday life to get more out of books at a faster pace with better comprehension."
If you have any more questions then please ask. I am not an expert at all though, this is just what works for me.