1/. From the documentation, SAP Informatuion Steward User Guide, section 2.9.6 View Uniqueness profile results:
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For both the unique and non-unique data in the bottom pane, the columns that are part of the uniqueness criteria are highlighted.
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This might be a bug 
, because the wrong columns are in bold. I get the same behaviour, but never noticed it 
.
2/. Uniqueness is based on full columns only.
3/. Uniqueness is based on the combination of columns you specify. That means for you that any combination of Address, City, Combined_Names, Company_Name and Country is unique. But that there are records having the same combination of City and Country (companies in the same city, obviously).