OK, solved part 2. Got the solution from Rainer:
http://rainer.4950.net/wordpress/?p=129#comment-67
You were right, whpalmer4, I just misunderstood. I was using an email file from Entourage to try to set the default app in Get Info. Of course that was already set to Entourage.
What I did the second time (and what worked) was to open Mail.app, make a new email, drag that email to the desktop and then assign THAT file (and 'Change All...") to Entourage. Presto. So thanks, all. I am loving life with a streamilined OF DB file...