When you enable supplemental logging in the oracle database, it will persist across reboots/bounces..
--Also you can see it yourself.. Check v$database.
--Enable the supplemental log , restart the db and query the appropriate columns in the V$DATABASE view to determine whether any supplemental logging is still enabled.. It will answer your question..
As for your other question, the tool that does the CDC , that executes the logminer should handle starting capturing changes.
If you are using Striim for this task, please visit
https://www.striim.com/docs/en/oracle-configuration.html