With WordPress.com, you can’t modify your blog in a sandbox and then promote it to production. Things will be unsettled for a couple of hours.
Update: OK, I think I’m done for now. I’m pretty confident the page nav problem is fixed (thanks to a custom menu). I killed the image at the top of the page to save on white space. We may not need the third column, but we will next week. The Twitter feed filters out all tweets that are just robotic notifications of new blog posts, so it is 100% non-redundant with the rest of the blog.
If the fonts are too small (most common problem, I think), read this (bottom section).