does this do more than using just a wire wheel to remove the rust?
I'll answer this question and it might help reinforce the first question.
This process actually reverses the rusting actually done to the bar, so treating rust this way turns the rust into a loose iron deposit that can be scrubbed off. So in a way it neutralizes the current rust so even if you don't get all of the deposits off it won't continue to spread. It also will leave a pretty attractive patina sometimes.
As for the first question, I got a full reaction down in the driver channel and got it treated so as soon as I drop a chain in and start running it, it should wear it out, but we will find out.