68. How do I enable email notification?

Go to Tools > Options > Email Preferences
Check this:
- "Display a notification message when new mail arrives" (disruptive, not often used).
- "Play a sound" (configured in Sound applet).
- "Show an envelope icon in the system tray."


69. Is there a way to alert me of something (e.g. appointment, new mail) even when Outlook is not opened?

There are a lot utilities listed at:
http://www.slipstick.com/addins/notify.htm

70. Reminders are not working in non-default folders.

Two ways I can think of: The easiest is to have two profiles, one for each account. Select the profile you want when Outlook starts. The other way is to have two accounts within the same profile, but do not schedule either for automatic receiving. Manually send/receive for each account. That way, messages arriving will be for the account for which you clicked "Send/Receive".

4. How do I set a default email account for sending mail?

Reminders will only fire in the default Calendar of your mailbox.
Check out: http://www.slovaktech.com for a tool that may help.