DPM Tape Backup

Hi,

I am taking backup in tape drive of my exchange 2010 mail boxes through DPM 2012. I have some questions;

1. My backup data base size is 1.1 TB. I have tape drive having capacity of 1.6 TB. i have define retention period for tape drive is 3 week with daily backup.My question is , Is this tape drive is enough capacity to hold three weeks data backup?
2. Is there any notification or indication in DPM when my tape drive will be full or require another one to proceed.
3. I want to take backup with following;

•     One week backup in one tape drive and will be used this tape drive after a month.
•     Monthly backup in every end of month.

Kindly guide me.