79. An "Operation Failed" error message appears after clicking Send/Receive.
You should create a new profile to fix this problem:
http://support.microsoft.com/default.aspx?scid=kb;en-us;312354

80. How do I enable/disable automatic Send/Receive?

Go to Tools > Options > Mail Setup > Send/Receive options.
Schedule an automatic send and receive every X minutes.

81. How do I activate the 'progress bar' for Send/Receive?

Go to Tools > SendReceive Settings > Show progress
Uncheck "Don't show this dialog during send/receive".

82. How should I troubleshoot mail that is stuck in the Outbox?

There are a lot of possible reasons for this behaviour:
http://support.microsoft.com/?id=195922

83. The Save Password Setting is not saved when I am connected to a POP3 Server.

You have to dig into the registry to try to eliminate this behaviour:
http://support.microsoft.com/default.aspx?scid=kb;en-us;290684

84. I am receiving duplicate emails.

Remove all the accounts that are creating duplicates.
Exit and restart Outlook a few times.
Recreate the accounts manually.