speed up the backup and recovery - how to recover only one schema

Database:                ORACLE11gR2NODE:                      5 nodes
OS:                          RHEL Server release 6.3
DB Size:                  18 TB
Back Duration:         55 hours.
Backup Nodes:        Backup running on 3 nodes due to licensing.
MAXPIECESIZE:       100 G each
DISK PARALLELISM: 3 Channels to Tape


I have the following questions:
1. how would I speed up the backup?
2. How would I speed up the restore?
3. how would I recover only one schema ? I understand that I will have to change my backup scripts.

Thanks.
Jack