Thank you. I only implemented good ideas of many people.
Widgets remembers initial orientation and stays in this orientation even you rotate device. This way it was designed from beginning and prevents many problems.
Current version 62 has bug which is there long time, sometimes on startup are widgets loaded in incorrect orientation, but I did not worked on that, because simple restart fixes it. But now, due immersive mode I rewrote some stuff and it will work correctly. This is related to that problem with right side described by you.
Walkthrough widget uses WebView control provided by android system (you can update it through google play). In reality it is simple web web browser. This supports txt files well (and probably images too), I can look at this. I am not sure about pdf. I will look at this in free time.
Yes, I know switching layers action is not very intuitive, I got several warning from users. I will think about it.