You may want to look at any sequences. By default, they will have been created with NOORDER which can cause unexpected results in a clustered database.
And for your other question, are you sure you want load balancing? You said that the purpose of the RAC was high availability, so i would think that you need to look at service and session failover, not load balancing.
Yes, primarily I was intending to say to high availability and from your response I need to look at the service and session failover aspects of RAC.
This is also brings a important point i.e. how can make sure that all the nodes are equally balanced ( load balancing) ?