Calendar Data, Windows 8.x and Live Mail

I am from a business IT background and have limited knowledge of consumer products.

I am assisting a neighbor who had Windows Live Mail 2012 on Windows 8.1 connected to their Bigpond.com mailbox.  They used their calendar religiously to record upcoming events.

They came to me when their machine couldn't successfully start Windows due to a corrupt registry.  I took a snapshot of the machine and rebuilt the box with the OEM media to reinstall Windows 8.1 plus apps.

A couple of questions

1. What files does Live mail store its data in (eg OLK standalone mode stores in PST's) and where are they.
2. Where is calendar data stored.  I have read a number of MS forum posts that all refer to Microsoft Accounts, however the user is adamant they don't have an MS account.  So I am assuming the data is stored elsewhere (Bigpond's servers perhaps?)
3. In the forum and support posts for Windows Live mail, posts referring to transferring data from one machine to another assumes you have access to a working system with Live Mail running, something this family no longer had.  How do I transfer data that I can recover from the backup to the newly rebuilt machine.

Any assistance is greatly appreciated