I've always thought that Angelina Jolie as she looked like ten years ago would have been perfect to play the role of Honor. She is - or was - very close to what I imagined Honor would look like, though maybe not as tall. Bit too old now, although if the effects of prolong are ignored then it could work. Of course, if it is going to be a multi-movie deal then a younger actress is preferable.
Not sure if on Basilisk Station is a good point to start, but the other books have just as many problems. Honor of the Queen might well incense the religious right, Short Victorious War would incense the political right (coughAfghanistanandIraqcough), and later books would miss out on all of the plot details and characterisation. Perhaps if they merged the third, fourth and fifth books together and started from there? You would bookend the movie with battles and have the whole "stomp all over her" in the middle.
I would rather see a Mutineer's Moon live-action movie made instead, it would be far easier to conceptualise and produce. And heck, we now have the same gravity-mapping technology that was proposed in the book.