when toggling off CREHeader, it doesn't keep book position, showing some past lines at new page start. I.e., previous page start is now showed at last lines of the new shown page...
Yes, you're right. When turning CREHeader on and off, a slight drift backward will happen. I noticed that when I implemented header, but was unable to resolve this. It also happens on Cool Reader 3.
CREngine uses 3 ways that I know of to reference offset. It's been a while since I worked with it, and I'm writing from memory, so it might not be completely accurate, but it looks something like this:
1. position, in bitmap lines from the top of the document of rendered text.
2. pages of the current selected font, font size and line spacing
3. xpointer - like a link to a specific paragraph.
The problem is, if you're in a page mode, it will align the first line on screen according to the pages mode, even if you issue a command to line up to position (1.). As you already noticed, page calculation is influenced with height of the screen. If you have header on, you have more pages. I hope this explanation makes some sense. I don't remember which I used, but believe me when I tell you that it's the best I could do. You just can't have page begin from the same line with both header on and off. It might be possible to save the possition, when you turn header off, and restore it when you turn it back on, but this complicates things a lot. There's no guarantee that user will just turn it off then immediatelly on. What if she turns a couple of pages? Then it would bring her back to the position she was at when she last had header on.
You might have better results if instead of turning CREheader off you switch to scroll mode and than back (scroll mode doesn't show header).
Regarding ScreenKB - Home does exit Librerator in Emulator. Why it doesn't on real K4NT - no idea, and I'm afraid I can't fix it without having the real K4NT myself.
It's ok when running Librerator from command line, but not when launching app from kindle interface using kite.
Also, running Librerator from kite does not go to last book (it opens folder view), and does not allows device go to sleep.
I don't know why this happens, and can't help with it. It seems LBR has problems if java framework is used to start it (look above for the problems with cr3runner - you were very wise not to try it before your trip).
Starting with FileChooser is normal behaviour. You'd need to modify librerator file in kite folder to make it open last document (you'd need to remove /mnt/us/documents part - but maybe you did that and it didn't work?)
Anyway, I made "Show last documents" first item in the Menu for a reason