No, it doesn't. The Intestate Succession Act will establish who your heirs are. This implies that the legislation determines who will inherit your estate.

A joint will is possible. The wishes of each spouse will be spelled dealt with individually.

No, you are not required to. In terms of your marriage, your spouse will be entitled to 50% of the joint estate, but you can donate your 50% to whoever you like.

You can draft your own will, but this might be risky since you may overlook essential terms. If this is not done correctly, you run the chance of the will not being approved by the Master, which means you will die without a will.

You had a valid will if you were testate. Intestate implies you died without a valid will or without having one.