Hi All,I went poking around and found some interesting books. Not all of them deal with Medieval Russia, for example the first book, Gwen might find of interest just from a "golly gee" POV.
Food and Drink in Medieval Polandby Maria DembinskaThe culinary history and eating habits of Medieval Poland was something previously unavailable or relatively inaccessible to a non-Polish audience. This book brings together evidence from archaeology, material culture and ethnography for the dietary habits at all social levels, from kings, queens and nobles, to peasants and monks. Includes thirty-five recipes for the reader to experiment with, and experience Polish cuisine at first-hand. 227p (Polish Academy of Sciences 1963, revised University of Pennsylvania Press 1999)ISBN 0812232240. Hardback available. Price US $29.95
The next one is a tad early, but may be good for background.
The Emergence of Rus 750-1200 by Simon Franklin and Jonathan Shepard Traces the progress and development of the realm of the `Rus' from its infancy to its maturation into a highly organised territory of prosperous towns with a common language, religion and leadership. 405p, 15 maps(Longman 1996)
Hardback. Price US $90.00
Paperback. Price US $36.00
Janos, you might find the next group of interest if you do not already possess them. They ould be very helpful with aspects of politics and history for you personae. 
Medieval Russia, 980-1584 by Janet Martin Comprehensive description of the major events and people during this period, which stretches from the the reign of Vladimir the Saint to that of Ivan the Terrible. 450p, 25 figs and illus (Cambridge UP 1995)
ISBN 0521362768. Hardback available. Price US $69.95
ISBN 0521368324. Paperback available. Price US $22.95
Medieval Russia: A Sourcebook, 850-1700 edited by Basil Dmytryshyn A selection of 70 translated documents illustrating the political, social, economic, religious, cultural, and legal life of Medieval Russians. 536p (Holt Rinehart, 3rd edition 1991)
ISBN 0030334225. Paperback available. Price US $48.00
Russia and the Mongol Yoke, 1221-1502
by Leo de Hartog Exploring a fascinating and little known period of Russian history, de Hartog traces the inexorable progress of the Mongol armies across eastern Europe, vividly recreating the destruction and terror that were their weapons of conquest. He describes the lives and careers of the khans and the princes who opposed them; the dynastic and political machinations by which Russia and its neighbouring states were riven; the gradual centralisation of power in Moscow as the Golden Horde's control over its empire dwindled; and the role of the Church as a unifying force. Finally, he discusses the extent to which the Mongols' had a lasting influence on Russia, and the means by which that influence was achieved. 212p, 5 maps, 5 tables (British Academic Press/Tauris 1996)
ISBN 1850439613. Hardback available. Price US $59.50
Enjoy 
Jenn