I couldn't find a category for Opera Mail, so I will just use this one.
This forum is perfect and you prefixed the thread title with "Opera Mail - ", which is also perfect.
I would like to know how I can find a list of unsent messages, or messages that are trying to be sent.
Is there something like this? A box for Draft Emails, Unsent Messages, etc...
"All Messages/Drafts" is for drafts. "All Messages/Outbox" is for queued messages or messages that didn't get sent because of an error etc. For both of those views, click the "Settings for this view" button on the message list toolbar and make sure "show sent" is set so that messages in there aren't hidden.
For messages in the Outbox, you can just delete them and Opera will stop trying to send them.