I'd go with David's suggestion of using Quizmaker as your development tool of choice due to it's ability to handle layering.
In terms of the video, you could really go one of three ways with this...
1. Forget the Green Screen. They're really geeky and all, but unless you're confident that you can get a really tight key and not cause
a noticeable drop in video quality, you might find that you're better off shooting against a nice backdrop and bringing the video
directly into Quizmaker and layering your text and other items over the top of the video.
But what fun is that, right?
2. Green Screen, If you're going with the green screen, I wouldn't add in a matching background and crop to match the
background image in Quizmaker. I fear that you'd have a difficult time getting these to match up perfectly and not be noticeable.
If you can get a nice clean key (say, with keylight in After Effects), I'd just bring in your talent with a completely transparent background
and then layer that over your Quiz Maker background. Or...
3. You could use the Green Screen, Key your footage, add the background, output that video, and then bring it into Quizmaker. Thereby saving yourself the need to worry about the background image in QM.
Either way, I might suggest that you use comp settings of 720x540 in your video editor and place your talent on the left edge. This will keep things simple and give you the confidence of knowing where your talent is on the screen. Just make sure that if your talent gesticulates a great deal, that if you want their entire body on the screen, that you leave room for their right arm to move in the frame!
Those are my 2 cents!