You can use REPLACE or CHARINDEX to see if it exists.

select 'ä', replace('lästname', 'ä', '-'), charindex('ä','lästname', 0)

If the numerator and denominator are in MB, you don't need to divide by 1024.

PercentUsed = Used/Total * 100

...

I wrote up how to use the HASH function to determine changes. Also, performs much faster then SCD.

http://anexinetbi.blogspot.com/2013/04/faster-slowly-changing-dimension-with.html