Answer 1

clustered index :
A clustered index sorts and stores the data rows of the table or view in order based on the clustered index key. The clustered index is implemented as a B-tree index structure that supports fast retrieval of the rows, based on their clustered index key values.
Non-clustered : A non-clustered index can be defined on a table or view with a clustered index or on a heap. Each index row in the nonclustered index contains the nonclustered key value and a row locator. This locator points to the data row in the clustered index or heap having the key value. The rows in the index are stored in the order of the index key values, but the data rows are not guaranteed to be in any particular order unless a clustered index is created on the table.
Unique : A unique index ensures that the index key contains no duplicate values and therefore every row in the table or view is in some way unique.
Uniqueness can be a property of both clustered and nonclustered indexes.