Featured image part is easy enough, you know what custom field is called, you just need to tweak it a bit for NOT EXISTS condition for it, see Custom Field Parameters in Codex.
Empty content is harder, that is not something WP_Query does. However in SQL it should be easy (content field equals empty string or along those lines) so you could run custom query via wpdb for that condition or add it via filter to WP_Query (which is probably overkill unless you really need these combined together, doesn’t seem it’s that important from description).