Lots of moving parts, but never say never. From what you indicate in your last post, at least part of the material is HD.
You want to do at least two things: get everything into a single editing ceodec (AIC), and conform the clips/sequences to a common frame rate. Same frame size would be nice, but not as important as the codec and rate.
I think your best approach would be to choose the format (size and frame rate) that the majority of your movie was shot in and create a new project and an AIC sequence with those settings. Then you could export your four finished sequences, conform as necessary and reimport them into your project as clips. You would finish and export as QT, current settings (AIC) and you'd have a movie file that could be re-purposed for DVD, the Web, projection, mobile, etc.
If you are able to buy ($49) and learn Compressor, it can do this very well. If you intend to do these sort of projects fairly often, the tool would be worth the investment of $ and time.
The other way would be to export using Quick Time Conversion.
Of course, there's always the option of starting all over and re-importing the footage…
It's been a while since I worked with FCE, amd perhaps someone else will chime in and point out some options that I'm over-looking.
Good luck.
Russ
