Yes, yes and yes.
I had to cancel two trips. Once due to a sudden accident and once to sudden illness of my travelling partner. It covered the both of us. It was an easy one page document that the Doctor signed. In fact the Doctor was surprised at how easy the insurance document was. Then i fiilled out a form online with the voyage number and booking reference, uploaded the document the Doctor signed and a cheque arrived within three weeks. Very hassle free.
Is Cunard Care expense. Perhaps. Insurance is always expensive if you don’t need it. Very cheap if you do need it.