You would only need FCP 4 if you were going to shoot on the 24p advanced setting. You can shoot in 60i or 24p(regular, F5) and have no problem with importing and editing the footage. The only issue that you may notice is that the audio may be two frames off from the video when imported. This has been something that has been corrected in FCP 4 but was an issue with version 3. But, if you don't notice it, then your audience definitely won't either.
As far as the Sony HDV, no one has a clue, apple doesn't release any information early about updates, or support for cameras. But, i'm guessing if they would like to please those users that they are working on supporting it in the next update.