is the bench made of solid real wood, or some kind of particle board?

The bench is made up of medium-density fibreboard - MDF. 

How much space is in the storage bench area?

Here are some secondary dimensions that will be of use
     21” – from floor to the bench      7.1” from the bottom shelf to mid shelf      8.3” from mid shelf to the bench

How much weight will the bench hold?

Weight capacity is 150-pounds.

What color is the metal frame (black, or dark brown)?

The metal frame is black.

Does this require assembly and if so it is easy to do.

This product does require assembly. Visit the product page and see the added feature bullet point labeled PRODUCT ASSEMBLY INSTRUCTIONS. Click on that to be taken to the assembly instructions. Starting on page 4 you can see the ease of assembly. This entryway organizer takes approximately 20 minutes to assemble. If you have any questions during assembly, please feel free to reach out customer service department at 877.242.2636.