I've been spending a lot of time sorting out my iPhoto life. I figure it will pay off in time-savings and efficiency pulling out the pics for my blogs.
In iPhoto, it is easy to select large numbers of photos to confirm that they contain the face iPhoto is naming. Just click on the area next to the photo and drag across the other photos.
If you want to reject large numbers, it's an additional step. Do the click-and-drag thing as above, but continue holding down while you also click on the option (alt) key.
To rename a photo, right click and select name, then type in the correct name of that face.
p.s. It would be AWESOME if you could click on any ad here - my sponsors give me a few cents per click. Thanks for supporting my blog!