Yeah, you have to filter based on some unique field - that was the bottom of step 5 above.
The part about returning the user to the form library should be automatic unless I'm missing something. I only use browser forms, and when mine are submitted or saved/closed, it returns the user to the form library. I actually use custom submit buttons with rules behind them instead of the built-in submit function, so maybe it's different, but if you look at the URL of your browser form when it's open, you will see a return URL embedded. This URL is typically the URL of the View the user was in when clicking New or clicking on an existing form. It always returns you to that view. When constructing a dynamic URL in a workflow or automated email, you can actually choose the return URL so that when someone submits or closes the form, it returns them to whatever URL you prefer (the same form library or some other location).
Oh, to be clear, I put a "close" action at the end of the set of actions on my submit buttons. This closes the form cleanly without the user having to do it, and it returns the user to the URL specified in the full Forms Server URL.