Questions re: mailboxes and PST files

I am looking to set up an adequate backup scheme to make sure all user’s emails are saved to tape. Here are my questions:

1) Is it possible via AD, Exchange System Manager, or some other method to configure all the Exchange accounts to send messages to their Exchange mailboxes rather than a local PST file? Or is my only option to log into each client’s Outlook application and configure it there?

2) Is it possible to take any local PST files that hold user’s emails and copy/merge these over to their mailboxes on the Exchange server?