Hi Martin
Good to hear from you again. I honestly don't think there is any magic answer to your main question. Just be good at what you do, keep track of the who's doing what in the TV and film business, and contact people! I always recommend teaming up with young student filmakers - today's students are tomorrow's film directors.
As for fees - always a difficult one. If you can get some idea of whether or not there is a reasonable budget for the project it will help you to be realistic in your quote. As you say, too high and you may price yourself out of the job, and too low and the potential employer may think you're cut-price and bargain-basement and possibly not up to the job!
Let me know the details on the stage production :
Cheers