Yes ! You can use this shark with blender 2.8 and render it with eevee. No modification required.

Yes. If you purchase this file you can use it for all you creations, commercial or not.

You just cannot sell this file but you can sell your work made with this model.

Not at all. You have nothing to do. Just move the camera then press the render button.

To make an animation, I recommend to use a curve modifier.