If you don't want to add the whole lighting scheme (understandably), there are some 'general' light sources you can add to the scene instead. I recommend the sphere shape and position it behind the camera, to act like a flash or those fancy studio lights that a profesional photographer would bring to light a scene.
2. I don't think it is a default hotkey, but mine is F10. You can set these in your work environment.
You can use physical renderer and if you do so, you can 'brighten' your image with the F-stop/Shutter speed settings of the physical camera. In this case you will prabably increment noise level as well. Before you go to the flash direction what Erwin mentioned, I suggest you to put area lights (softboxes) to the windows/doors, this way the result will be more natural.