I am someone evaluating the product for data replication between heterogenous databases. My question: 1. If the primary keys are not signed as primary key in the DDL, so I cannot use incremental replication is it true and the rule "the primary keys in source should well be defined"? for replication method "CDC"

For CDC you need to have a primary key declared in your DDL, but for incremental sync without CDC is possible to have only a field that works a primary key.