I just got a copy of James Arnold's book Crisis in the Snows: Russia confronts Napoleon - The Eylau Campaign 1806-1807. It seems to be the one of the most (if not the most) detailed account of the campaign I have seen to to-date. Almost 400 pages (with 37 maps!) of detailed analysis of the campaign, plus fifty pages of appendices (various data, OOBs, etc.).

Best wishes,
Alex