Hello Chokkie,
try clicking on the CONTACTS tab, on the left hand side does LIST show? There might be a + by it, click that, this might allow you to recreate your "circulation lists", viz create a new LIST name and drag and drop the contacts into the new LIST name. At best it might even show the "lists" you created before changing to the new Yahoo mail.
I have no idea about secondary e-mail addresses and being able to switch between them.
In all honesty I'm happy with the new format. Sorry I haven't been quick enough to help with any of your DT questions!