Is it possible to set 2 methods on before_validation in the model?
before_validation :elaborate before_validation :download_remote_data, :if => :data_url_provided?
Yes, your code is ok. Just keep in mind that a complex method will be executed first (since it registered before the download_remote_data method).
This is certainly true. You can add as many before_validation calls as you need.
before_validation