They didn't "fail to repay." Nobody ever repays this type of loan. They failed to refinance. And the fact that no one would refinance their $725 million loan means that the property has seriously declined in value.
Largely, but not strictly true. When the property changes hands, the old loan is paid down by the original owner / creditor and a new loan is taken out by the new owner / creditor.
Not really.
If I buy a house with a mortgage, I wouldn't say I refinanced the house just because the previous owners also had a mortgage. Refinance is only used when the owner is the same across loans.