jayeff

I'm a long way from being convinced that duplicate content within a single site is actually an issue. I have always made it is easy as possible for SE's and surfers to find articles by whatever route suits them and I have never been aware of any problems as a result.

Anything is possible, but it really wouldn't be rational for Google, since its people know how blogs are structured, to penalize the ability to view the material in several ways.

However, if you do buy into these concerns, logically you would index the main page and pages, then take your pick from one of categories, archives or single posts. I would suggest leaving follow on throughout and just restrict indexing. If you are pulling in feeds, it might be a good idea to exclude that content, if you have a way to do so.

Surprisingly painless as a rule. You should check that any critical plugins are compatible, because some still have to catch up. Otherwise the only snag you may hit is that some forms of reference to the blogroll no longer work. If that catches you out, the fix is easy.

I strongly recommend backing up your database and installation, then deleting all your WP files (not the database tho), so you can be sure that nothing is lurking from the old setup.