VonHaus 12 x Decorative Collage Picture Frames for Multiple 4x6 Photos - Black Wooden Hanging Wall Photo Frame with 12 Openings Hooks Included

Hooks for hanging - are they permanently attached to frame's border? If so, are there two different set of hooks for hanging in either direction?

Does it need to be nailed or can damage free strips that are removable be used?

Does each individual picture frame have its own glass?

Is the back covered by one large piece of cardboard, or does each picture have it's own opening?