2.1 How can I programtically add fields to a module, something similar to the get_module_fields REST endpoint but a set_module_fields?
2.2 Can I use the set_entries REST endpoint to do bulk import of data?
Sorry, I really don’t know much about the API, never used it.
About the bulk import - any reason why you would want to do this through the API? If it’s just a one-time, initial import, I would do it more directly, via SQL to the database, or if it’s more structured and nuanced, through an import script which runs as a custom entrypoint and uses Beans to write data.