Thanks Toritoribe. So, does #4 mean "Did Junko's friend think 'Why does the man not have a girlfriend?' "? Somehow I am still not sure if I have grasped this properly.
Mike, some of the sentences I ask about are from tatoeba.org and are isolated. I try to read a few of these at random each day, mostly to try to expand my vocab, which is poor. However, most of the sentences are from textbooks and are typically from mini-stories, essays, dialogues, and sometimes excerpts from books, newspapers and magazines, etc., or whatever material the textbook decides to use. Also some are from textbook exercises that explain particular grammar or structure points. Often there is lots of context: I might read half a page of a story before I hit a problem sentence. However, to save time and space here I only mention context points that I think are necessary to inform the meaning. Thanks for your book offer; I have several "proper" Japanese books, and of course plenty of "proper" Japanese available via the Internet. I hope to progress to those things in due course, but for now they are still a bit too hard for me.