Premiere Pro project setup and exporting 16x9 to 4:3 letterbox

I need to export a 16x9, 720/30p CS3 project, for final viewing on a 4:3 projector in letterbox. *This project is about to kick off with a VERY short deadling and the shooters keep changing their mind about whether they're going to shoot in 720/30p or 720/60p. I need to plan for both to be safe. How will this effect things in my original 16x9 project setup if they give me both 720/30p and 720/60p video? And what about exporting for letterbox viewing in 4:3 if this occurs? I mean, if I start a project in 720/30p with CS3 and they bring me 720/60p video as well as 720/30p video, will I have to start a new project and start editing everything all over again, and vice versa? Also, how will this effect my final letterboxed 16x9 product? **I also have to provide this to the customer in 16x9 DVD format.