Hello Luis.
Answering your questions.
1. Idempiere is ready for Prod, ( we are using for 2 customers at this time), and extending with plug-ins for new solutions.
2. Regarding infrastructure, Idempiere requires a OSGi container(service & platform) ... currently, we use Apache Felix by default including admin console, tomcat container intergation and so on, performed by the core team.
But because OSGi is pretty standard, you might be able to deploy Idempeire with any other OSGi standard container (werbsphere, weblogic, and so on),,,and dependieng of your container you might be able to configure complex enviroments such as clusters for replication, performance and so on. If you are not familiar with advanced OSGi deployments like those, you migth need professional consultant services.
BTW: Wwe are pretty familair with Websphere, Weblogic, JBOSS and OSG environment if you need professional help handy,
Regards
Pedro Rozo.