The G25 pedals will work with the Fanatec wheel, but it's not like you can just plug the pedals into the Xbox and they magically work. The pedals themselves don't have a USB device ID (nor do they even connect using USB), so you need a device with the proper connection (either USB or wireless) and a device ID that the Xbox recognizes.
I already mentioned that the G25 pedals would require some modifications to work with the 360, nor did i say that you could plug them straight in and expect them to work. Please read my post again properly next time before trying to correct me.
I don't know how the Microsoft system works but I would of thought if you keep your xbox off live until official release it should be ok as they wouldn't know (unless they can look at the date the game appeared on your gamercard or something similar).
On a slight off topic-ness: It seems the postal strike is held off for a couple of days but looking still likely to happen. If it does though, it will be around Thursday/Friday next week Perfect timing to interfere with the delivery of FM3. I don't know about anyone else, but I reserved with GAME as well and the one by me opens at 8am so should (if all goes to plan) be able to pick it up before work on Friday
If I'd thought about the strikes I'd have done the same thing, and just gone to my local store to collect it. I guess it's not the end of the world if it takes another couple of days to arrive. If only I could update my order...