Hi @ktbg, thanks for your feedback!
For your first question, the column editor currently does not expose the source key, so the label must be manually updated. The team will look into adding better heuristics for the auto-name generation to ignore suffixes like __c to reduce the amount of manual work required for column names with this type of format.
For the second question, including a reference to column key as you do in {{currentSelectedRow.Job_Function__c.readOnly===false}} is currently the best way to accomplish this, as the editor does not expose any data that would allow you to derive Job_Function__c programmatically.
These workarounds should hopefully solve what you're looking for! The team is currently looking into dynamic column support for the new Table, and in the meantime dynamic column settings are still accessible in the legacy table if you need them. Stay tuned for further improvements here!