A1: Depending on your database engine and view construction, it may be possible to update a view. This makes no more sense to me than updating a SELECT.
A2: Stored procedures are a better alternative in my opinion.
A3: Views provide security in many ways. They allow the base tables to be left secured (no permissions need to be granted on the base tables). They allow the administrator to restrict which columns of which tables the user can see. Views also allow the developer/administrator to "bury" complex logic needed to get correct answers, while still making that logic easily accessible to end users.
-PatP