The only current e-book reader that is even close to your needs is the iLiad. It has the largest available E-Ink screen (8.1"). The device is essentially A5 size, and the screen is a bit smaller than that. It can read letter/A4 PDFs comfortably (zoom to remove margins, and perhaps flip to landscape and show half a page per screen). It also does note taking (Wacom Penabled touch screen), but the notes need a companion Windows PC program for character recognition etcetera. For DOC files, you should probably convert to PDF first on a PC and then read as PDF on the iLiad. The iLiad has a much shorter battery life than other E-Ink devices, but it lasts at least 15 hours. There are several threads with photos of the iLiad reading PDFs, for example Technical Document Examples
and Photos from medical journals
. Note that the medical thread includes both photos and screenshots (copies of the display bitmap). Also, both photos and screenshots may be scaled by your web browser to fit the screen. If so, click on them again to get the full effect.
If the iLiad is too small, then you should look at tablet PCs - but battery life is typically short.