Re clause 4: You can delete it if you are not aware of any circumstances which might call capacity into question.
Re clause 5: Instead of the type of wording in the example, here you can deal with any prior executor named in the will if there is any. For example, if your father is the deceased and your mother was the first executor named in the will (but had died previously), you would state the details of her predeceasing and
annex a copy of her death certificate. If you're the sole, primary executor - no need to worry.