2. On ALL my messages, whether they appeared properly first or not, when I click "Get Plain Text" the entire content of the message disappears.
We don't have that problem and we are on 4.1.6, XCH 2007, OL 2007. So I am not really sure if TS is right. It is of course easy to say "the next version will solve all your problems".
You can check in the mail source, if an AV product has really altered it. Also, try switching off the AV tempararily.