Yes, Siddhi is just a Java Library that can be embedded to any system.
No, WSO2 only provide support for Siddhi.
Yes, there is a way to trace events through the CEP. See CEP Event Tracer.
Yes, CEP 3.0.0 onwards has support for JMS queue.
Yes, see Writing Custom Event Adapters.
CEP only supports for Siddhi processing engine.
Yes, It is possible to writ extensions to CEP. See Writing Extensions to Siddhi.
There are two ways to send notifications. They are Email and SMS.
CEP supports any JMS brokers. WSO2 have tested with activemq, qpid, JMS and WSO2 Message Broker.
Yes, pattern matching is possible in Siddhi. See Patterns.