As Doug said above:
It's better to just use the ipr file.
There's no need to render a movie in LiveType, unless it is going to be used stand alone. Save the LT project file (it has the .ipr ending) bring that into FCE -you can treat this file exactly as if it were a video clip, plus you only need to right click and choose Open in Editor to jump back into LiveType, should you need to change something.
You will need to render the .ipr file once.
Rendering a movie from LiveType means you have to render it twice -once to make the movie and a second render for it to be playable in the FCE Timeline.