1. You will want to create your own server configuration. So copy one of the server directories, like "default" and give it a new name. Then when you startup jboss use the -c like "run -c myconfig"
The other thing you have to do is make sure the ports don't colide. If one instance is using the default ports, the other instance must use different ones.
In the samples directory, in one of the sub-directories is a samples-bindings.xml and in there there are ports configured with names like ports-01 ports-01. You can use this too, but you have to point each server to one of them through the jboss-service.xml file.
Check out the Admin guide at jboss's website for complete directions.