I don't think you can type on the e-ink side at all, with the internal keyboard or an external one. Editing on the e-ink side would be like a Sony, but with more possibilities. You can attach notes, web pages, documents, recordings to your epub or pdf. You can copy sections from the e-ink side onto a document on the LCD side. You can email your pdf (probably epub, too) from the e-ink side through the email function on the LCD side.
You might be able to do rich text editing on the LCD side (probably can), but a PC can do it better. Just depends on what you want! For me, if I ever get back to it, I will probably sit with my laptop in front of me and my PE to the side, with notes and plans and research on the PE and active input going to my laptop, then maybe sent to the PE so I can retire to my comfortable chair for rereading and editing.
The forums have been working well for the last week or so . . . drop by!