Even though this post is very well prepared in general, I'd consider it a case for a "Failed to search" alert, since precisely the information looked for can be easily found:
http://service.sap.com/sap/support/notes/2112604
--> FAQ SAP HANA Compression
describes in quite some detail most practical aspects around compression in SAP HANA.
I recall having explained this topic myself several times here on SCN, too.
Please always search before post 
!