Around the time the HTC One becomes available for people to pick up, HTC will update their HTCSync software. It will let iPhone users converting over the ability to take a backup of their data from iTunes and directly sync it to their HTC One. This includes all the mentioned items and also includes text messages. HTCSyn is compatible on Mac and PC right now and we assume they will keep with that since it is focused on converting iPhone users to Android.
No one can predict if a flood of iPhone users will go out and pick up a HTC One or not. At least those that do make the transition will have an easy way to get up and running with where they left off, for the most part.