Thank you for your interest ! For text notes, you can see it at 1:30 in this video, but if you want to see the graphical note feature, you can see it in our other video Read and annotate an EPUB at 2:10 (the same feature is available for PDF and EPUB indifferently).
Yes, you can see the book in a Landscape or Portrait orientation of the screen as well (horizontal or vertical). You will see this too in the sequence about graphical notes that I mentioned.
Yes, the dictionary works for PDFs. And yes you can add dictionaries, either by downloading them in a predefined list or by using Colordict, since the reader is compatible with it.