Hi everyone. We are also a couple from Australia, and very excited to go on this cruise. Just to help with some of the above questions. We are flying in two days before too and have booked a Covid test appointment with Bluemed Home Health Care via Whatsapp (great communication and easy to organise). Also followed this link for getting a visa for Sauda which it is currently under process but it worked and didnt take too long to do. My partner advised the bank first that there would be a small payment and all processed well. A couple of pre-info tips, you need to document what countries you have visited in the last five years including dates?, pay for medical insurance (a selection to choose from) by quite reasonable and pay for the visa in three payment processes one for medical insurance, one for processing and one for medical something else. It can to approx. $44 AUD. Here is the link to where you access the portal and one to follow how to fill it out. Hope this helps.
https://visa.mofa.gov.sa/Account/LoginIndividuals
https://msccruisesksa.com/saudi-arabia-travel-documents-visas/