You're likely going to need dynamic SQL to fully implement essentially free-form conditions, but to do what you've specified so far, you can do it with just standard LIKEs:

I believe session_ids can be re-used, so getting a session_id wouldn't necessarily tell you anything.

As noted, if you need to get that info, add a trigger to capture...

Yes, for testing purposes, adding an identity to guarantee uniqueness should work just fine.

After shrinks, I've had good luck very often with just a REORGANIZE overall ~80-85%, rebuild required ~15-20% of the time.  Start with the smaller tables first, moving up in size...

For storing of SSN, you might consider adding a check digit to the value, so that it does become 10 digits (or 11 or whatever).  That way they are trying...

You could use a SEQUENCE, or if that is not available, insert the SSN into table with an identity and use the identity value as a link back to the...

Select Code, new_string
FROM #Temp
CROSS APPLY (
    SELECT STUFF(Code, 1, 1, '') AS base_string
) AS ca1
CROSS APPLY (
    SELECT LEFT(base_string,...