Hi Osslotto,
First, I strongly suggest you have your will drafted (or at least looked over and approved) by a lawyer. The benefit of this is, firstly, there are certain requirements that must be met for a will to be valid (e.g. witnessing and attestation, formalities). A self-drafted will may not be clear enough and may get confusing when the time comes to administer (e.g. if you wish to have an animal welfare organisation as beneficiary, what if they close down or change name between now and your death? In this case, and you have not made proper arrangements in your will, the gift will fail and will likely fall into intestacy). Secondly, the will can be safely kept at the lawyer's office and when the time comes, they will contact the executor and assist in administering the will. The lawyer can also be instructed, by you, to not show anyone the will until your death, and only then, to show the executor. A lawyer, as your agent, must comply with your instructions and are bound to privacy under the duty of confidentiality to clients.
Now to your questions:
1. Yes. Before death, no-body, except you as the will-maker, has a right to see the will (without your consent). This is because, anything written on the will is a mere possibility. They are not expectations. You can change your will whenever, however many times you like. Hence, any person named in the will has no right to your estate until distribution.
2. The bank must honour your will under law (provided, the gift is valid and enforceable). You do not need to worry about this. Banks are experienced with honouring gifts under wills. Same with your superannuation fund (note: super is not covered under the will and cannot be "left" to someone. If you want to gift unused super to someone, you will need to contact your super fund and make a "binding death benefit nomination" otherwise, your fund gets to choose who to leave the money to).
3. Yes. You can appoint a beneficiary as your executor. You should get their consent first. Also, you should always have a backup executor, in case the primary executor predeceases you, cannot be found or refuses to be an executor. A beneficiary should not be a witness to the will. Whilst it will not make them lose their gift under the will, the courts may treat it as suspicious. So best to have two uninterested witnesses.