Thanks for both your answers John. About moving includelets, I did eventually work out for myself why I couldn't move them.
About the breadcrumb trail, I don't think it's necessary at present, but it's possible that the website will grow into a more complicated structure, and then it will be useful. So I think I'll leave it as it is, but if you want something to pass the time, you could write something here about it, and it may be useful to other people.
Incidentally, the second item in the breadcrumb trail shows as "Content" in Preview, but as the name of the current page when I look at the actual website. So much for WYSIWYG.