you can retrieve all sinks (that you are allowed to see) with getSinks() and and all information about sources with getStreamsAndViewsInformation() (I think there could be a better name
Sources are created when you use := or ::= in PQL. If you do not need explicit sources/sinks you can just use access/sender operators in queries. In this case the sources and sink are removed automatically if all queries that use these sources/sinks are removed.
Hope that answers your question?