[OT] Secure connection to email servers?

[walt]

Background:  I have free email accounts with myrealbox.com
and gmail.com.  Both organizations provide TLS connection
to outgoing (SMTP) servers, and SSL connection to incoming
(POP/IMAP) servers.
My questions:

1.  Why use two different protocols instead of one?
2.  Does the use of secure connections make the 'secure
    authentication' protocol irrelevant?  (I notice that
    my password never appears in the clear in either
    direction, even though I don't use 'secure auth'.)
Thanks to any security guru who can explain!