Anthony,

Those sound like some good ideas for tutorials hopefully they will do some of them though they already have interior and exterior tutorials for houses and the techniques taught in them just need some slight adaptations to build a castle. Check out the Taj Mahal tut here it is really good for teaching building techniques.

also these ideas are big tasks that usually are taken on by a team of people not a single person, and you have to consider what the purpose of it would be. Most productions "i.e.movies" don't ever bother modeling entire structures just scenes but I still like the ideas.