I suspect something gets hosed if you ever set the authentication that prevents you from getting back to plane old Auto and only that version of auto works (at least with godaddy.
Possible. Not sure. As for having to retype your username or password sometimes. That's something a lot (but not all) Opera Mail users have to do sometimes. I don't think anyone has figured out why it's needed. Something might get corrupted with wand.dat (the password file) or somehow tweaking some of the server settings causes the saved entry to be invalidated, or something with the password dialog that pops up (if you don't have a password saved), doesn't set things correctly where it messes things up. It's weird, but something that happens a lot for some.