but it's basically a representation of each table in Moodle nested as every "graphic" drawn in each module "backuplib.php". Central tables (users, courses, section...) are easy, I think...
Anyway, if somebody want to start writing it, I'll help for each question in (not inmediatly, but 1-2 days, sure), but I'm very busy now and next months are going to be very stressful for me at work... without mention your 1st question (in a pool of 5) recently written in another discussion.
Ciao