The Oracle license is the "right to use" (RTU) the software and not the software itself. If you have a license, you can obtain a copy of the software.
Licenses are not tied to the product version. For example, an Enterprise Edition database license is equally valid for Oracle 9i, Oracle 10g or Oracle 11g. However, you are only entitled to new versions if you have a valid maintenance and support contract in place.
Licensing Cost Metrics
Processor licensing - You pay per Processor you run the Oracle software on, no matter how many database you will create.
Named User Plus Licensing - Pay per user, however user is defined as any end-node that receives data from or creates data for that Oracle DB including human users.
Anyway Oracle does not license by Database Instance.
So my answer is :
1) If same cluster nodes no additional license is necessary
2) If a new node, new license is necessary.
So can I have a simple stand alone instance on existing h/w using some portion of SAN for reporting?