Welcome to the Forum!
To elaborate on the tie wraps. The black mesh inserts and plastic windscreen have a nasty habit of flying off the car on the rare occasion. People take preventative measures because replacing these parts can run about $250+, so people will use zip-ties on the mesh screens.
On the windscreen you may want to drill a small hole and use a zip-tie, or just do nothing. Mine fits tight and doesn't rattle, so I don't mess with it. Once again the flying away thing is rare but can happen.
Also, there is some debate about the usefulness of the mesh inserts. I prefer to leave them out because the wind noise reduction is small (if any noise is reduced), and they can block a lot of reward visibility depending on your height. I would play around with the inserts and windscreen and see how you feel about how well they stay in.
Also, I completely agree about the Bentley Manual. I got mine at Christmas, and it is the Bible for Boxsters! It has just about everything you could want to know about a Boxster in it!