Do all cluster members need to have the same root password?
You are not required to have the same root password on each cluster member. However, you can simplify administration of the cluster by using the same root password on all nodes.
Is the order in which nodes are booted significant?
In most cases, no. However, the boot order is important to prevent amnesia (refer to "Quorum and Quorum Devices" for details on amnesia). For example, if node two was the owner of the quorum device and node one is down, and then you bring node two down, you must bring up node two before bringing back node one. This prevents you from accidentally bringing up a node with out of date cluster configuration information.
Do I need to mirror local disks in a cluster node?
Yes. Though this mirroring is not a requirement, mirroring the cluster node's disks precludes against a non-mirrored disk failure taking down the node. The downside to mirroring a cluster node's local disks is more system administration overhead.
What are the cluster member backup issues?
You can use several backup methods for a cluster. One method is to have a node as the backup node with a tape drive/library attached. Then use the cluster file system to back up the data. Do not connect this node to the shared disks.
See the Sun Cluster 3.0 System Administration Guide for additional information on backup and restore procedures.