Answer to 2 is easy. Yes, you will lose all data in your apps, unless they somehow sync to the cloud somewhere. Like, Angry Birds recently introduced a feature where you can create an account with them to save your game progress. Without such a feature, your game progress is lost if you switch to a new device and set it up as new.
Reason why people warn against restoring from backup. IMO, this is not relevant unless you have jailbroken or have used beta versions of iOS. When you do either of these things, there could be things in your backup that can potentially mess up your system. Even with stock OS, there is a slight possibility that things could creep in to your backup that could cause slowdowns or problems in your system. But overall, my advice is to just restore from backup and enjoy your device. If you find your system does develop problems, you can always restore as new AFTER you actually experience problems. To give up the benefits of restoring from backup in order to preemptively avoid problems that may not even happen seems paranoid to me.