Well, first I would add in the RECOVERY option to the restore.

Second, it sounds like you are out of resources to do the restore.  how much free space...

I think to encapsulate it you would need to put it into a UDF but as you said that'd be a RBAR thing and you are trying to avoid those....

The other option, presuming you have SQL Enterprise or SQL 2016 SP1, is to use change data capture.
https://technet.microsoft.com/en-us/library/bb522489(v=sql.105).aspx

how about this:
SELECT CAST(ABS(CAST(CAST(FirstDate AS DATETIME) AS INT) - CAST(CAST(SecondDate AS DATETIME) AS INT)) AS INT)/365
Not positive that outer cast to an INT is required, but...

I did this recently on our test box.  I just used the SQL 2016 installer to do this.  I clicked on the upgrade button and let it do its magic....

What is in the log AFTER the differential restore?

And what is your full restore command?  What about if you remove all of the optional arguments and just stick...

Is there a reason you want the databases on the cloud though?  Is this something customers are requesting or your company is thinking is a good idea?  I am just...

SSRS runs in separate memory space from the SQL Server Instance.  So if you have 24 GB allocated to SQL Server and 24 GB limit set to SSRS, it is...