Role of Database Administrators I am currently working as an application developer on a project which involves the creation of a new SQL Server database. I am actively working with a group of DBAs who will play some role in the creation and maintenence of this database. 

I want to understand what role the DBA normally plays in this type of scenario. It seems the DBAs consider everything to be the responsibility of the application team. I designed the schema and indexes, generated the DDL, and am currently in the process of performance testing the database. Are these tasks normally performed by development?

Also, it has been suggested that development should be responsible for the creation and maintenence of the database user accounts. We would be responsible for periodically changing the passwords on the production databases. Is this the norm? It seems to me that it should be done by the DBAs.
Of the tasks that you've listed the creation and maintenance of the user accounts in production should be done by the DBAs.  The developers shouldn't have the passwords of the production accounts at all.

Designing the tables, indexes and performance testing should all be done by the developer.  The DBA should be handling the creation of the objects on the production server, backups, etc.  The DBA will find any additional indexes which are needed after the system goes into production and create them in production.