Starting the web server in development and production are totally different.
nginx and gunicorn are not used in development.
You should do a bench init frappe-bench, this will be by default set up as development bench for you. Then, you can restore your database from your production setup.
To copy customizations, you can Import/Export your Custom Field DocType or/and export fixtures. Please go through the following articles to know more.
https://frappe.io/docs/user/en/guides/app-development
https://frappe.io/docs/user/en/guides/app-development/exporting-customizations