I have diagnosed part of my problem.
The QuickRSS plugin I had active on my site was not playing nicely with the built-in RSS fetch in the WordPress 2.8 administration panel.
I deactivated the plugin, and that problem is solved.
However, I still have no access to the visual editor.
I am scrolling around the blogesphere to see the problems other have before I upgrade. Having had problems in the past, accompanied by palpitations, I now wait.
try reselecting your theme and then check it out…