Three adjustable legs. Many of these only have two.
Tray is about 10.5" x 17". Overall, 10.5" x about 20".
Two cooling fans. Plug the USB cable into a laptop.
The standing height in the pictures is about 15" to 16". It can go as low as you want. It can go a bit higher, the legs can be straightened, but it's not as sturdy then.