It will cost a small fortune to make it suitable to have fish, (Even then it would be only two) I would be inclined to fill it with water, put a brick on its end on the shelf (so wild life can use it as a step) and leave it and see what decides to move in.
Don't put the gravel back in, people used to do it because that's what you do with fish tanks, trouble is people with fish tanks soon learn that you must clean the gravel, try doing that with a pond.
As for the water spitter (Gnome in your case) you need a small mains pump. But small mains pumps often clog quickly, and don't come with hose tails
This is an example of a stepped hose tail. (Its what you use to connect the pump to the spitter hose)
If you were thinking of solar, I suggest you read THIS first, besides a "natural pond" does not have a fountain, water spitter, water feature etc, and Lilies don't like moving water.
Speaking of lilies, there is no reason you can't add some aquatic plants.
Good pictures by the way.
Good quality costs. Bear this in mind before you start.
Sorry if my reply is NOT want you want to hear, but what I have said is true.
Yeah I had to empty it all out, It was a mess, plastic bottles in there old water pump parts. Had to be sure it was completly clear. I might maybe leave the water feature part for now, will have a think. I heard moving water attracted birds you see.
I think I will try a few cheap plants in there. Had it been a lot bigger I would have put fish in it, hoping for local wildlife to make use of it, so will look at putting bricks on the shelves also.