If you have moved the content elsewhere, 301 Permanent Redirect should be used, as it passes all(well most) the old pages link value e.t.c. to the new page

If it's temporarly elsewhere, 302

If it's gone for good and not coming back and theres nowhere apropriate to send people, consider 410 gone.

If you mean what status code should your missing pages/bad urls return, that should be 404, not 3XX. Redirecting the user to a 'error' page with a 301 that then returns 200 ok is a great way to have a lot of problems and little way of spotting them.

There are meny crawl tools out there, but Xenu is the one I would recomend for this. It will crawl your site, and then at the end ask for your ftp details so it can specificaly check for ophaned pages. That should make the report you need.

*edit - here's the link: http://home.snafu.de/tilman/xenulink.html

If you have nofollow on all the pages, there is a chance it is being caused because google can't follow any links to your pages tho crawl and update them with the no-index tag.

Try changing your links to noindex, follow.

Since most people leave them off, and most people link that way and it's easyer to set up I have site wide slash removals.

You get a 301 regardless if people link to you wrongly, so be carful when giving out the url and internal linking you use the right on either way.

I'm also not convinced that the article quoted is right in saying that the server does a 301 when you leave it off. It certainly has to do an extra lookup stage to find the right file(look for file, not find, look for directory with defualt document), but theres no 301 header returned.