By "'a rest' of the previous page" do you mean ghosting (like a really faded out image of what was there before)? That's pretty common, but it is something that is most pronounced when the Reader's been idle for a while, and diminishes after a few page changes. There's not really anything other than that you can do about it -- most folks find it comparable to the 'show through' on paper pages.
For BookDesigner, the interface does have an English setting (my Russian is non-existent too
), you can find what you need to download in
this thread -- the main install files are linked in the first post, but you'll need to look at the end of the thread for links to the updates (post 134 seems to have the most recent one at the moment).