(1) Yes. AthenaX provides a thin wrapper of KafkaJsonTableSource[1] out-of-the-box. As long as you specify the schema it should be good to go.
(2) Your guess is correct. Internally we have AthenaX streaming data to MemSQL, Pinot or MySQL to support the use case you described. Some of them go through the JDBCTableSink [2], the others go through a customized connectors. AthenaX is designed to allow plugging in connectors when required.