Preventing frequently updated nodes from keeping them on the top of View
Not possible using views out of the box! Because updated date is stored as a single value in the database. If a user updates again the new value overrides old value.

So, there is no way views can track within one week after their last update even if they update it again . 

You need to use hook_nodeapi either to track all updates in separate table and query that table to list users.