Moving WordPress – old posts?

I didn’t see this answer in any of the moving WordPress posts…

I’d like to move my blog from it’s subdirectory to the root directory (so instead of the blog domain of “http://blog.*.com”, the blog will now be the home page at “http://www.*.com”. I read that leaving it in the subdirectory but pointing it to the root will not give you the Edit link next to the posts when logged in, so I’d prefer to move it.).

The wordpress instructions at http://codex.wordpress.org/Moving_WordPress are pretty straightforward, but it doesn’t explain what will happen to the addresses of the old or existing posts. Can I assume that any old posts referenced on another blog will NOT lead visitors to the correct location for that post in my blog AFTER I make the move?

Would leaving it in the subdirectory, but pointing to the root directory (per http://codex.wordpress.org/Giving_WordPress_Its_Own_Directory) resolve this issue (but not provide the Edit link as I described above)?

Or will any change mess-up the links to old posts?

Fyi: I have discovered in testing that if I add an index.php page with a redirect (<?php header (“Location: http://www.homepage.com/index.php&#8221;);
?>) in the old subdirectory, and then enter the url of an old post in the browser, that it will redirect to the new home page. But I’m curious to know if the url of an old post could somehow still be good after I make the move, or if second option would resolve that issue (http://codex.wordpress.org/Giving_WordPress_Its_Own_Directory).