If you are interested in ordering Russian books for the children to read, you can order them from www.kniga.com .  The website is in Russian, so you may need help from an interpreter.  You can send an email requesting specific books.  Other parents have phoned them directly and gotten assistance at (718) 743-4054. Of course, the easiest way is to ask your interpreter to help you on one of her visits to your house! 

You can also obtain Christian books, Bibles, and literature from www.russianpublishing.com.

If you are interested in setting up a ‘lending library' for the children's visit, you can coordinate with other families via the yahoo loop. 
Another useful book, Children's Illustrated Russian Dictionary by Hippocrene, was found at Borders in the children's foreign language section.  The ISBN is 0-78018-0892-8 2002.

A free Russian dictionary is on the web site:  www.learnrussian.net/links.html