Analogus
just my two cents:
1) there is a var kbook.model.STATE, it can be "MENU_HOME" or something like "PAGE_GROUP" you can check for this to see if the book is open.
2) brave! This is somewhere within the skin.styles[] array. Sorry no more info on that
3) Put a IF FI clause in prsp.sh which checks for your additional font-changing script and call it, when present.
Have you checked:
http://tortoisehg.sourceforge.net/ as mercurial frontend for windows?