1. Sealed orders are official and can be used as evidence of the order, such as if you need to register the order in another court or jurisdiction.
2. Orders are usually signed and sealed by a Registrar, by physically placing it in front of them and having them verify the correctness. The courts charge for this, and you don't pay the fee unless you need it sealed.
Also, quite a few courts now have copies of their orders available on the internet. For example: the Federal Court. You're not going to get a sealed copy of the orders on there in case they've been altered in some way.
3. Nope. The order is the order of a court - not a person. You'll get a designation and the seal of the court. In essence it's similar to a company's execution - there you get the 'seal' of the company (especially if they still have a common seal), a signature and the designation of the signer (e.g. director). The important thing is: the 'signature' of the court is the seal. The person signing is to attest that the seal has been properly affixed by someone in the position to do so.
4. What I mean is, so long as that is the correct order that was made by the court then there is nothing wrong with it. It's merely a copy of what the actual order is - the same as if you'd written it down word for word from what the magistrate said. The only official proof that that is the actual order is a sealed copy by the court. An unsealed copy doesn't mean that the information is wrong, it just can't be used as proof of correctness.
To explain by analogy: I have an autographed photo of Elvis that he gave me (i.e. the order). I know it's real, but no one else believes me. If I have a Certificate of Authenticity to go with it (i.e. a sealed copy of the order), then people will believe me.