Hey Blu Tang,
If you are just going to do FOWLR I would probably skip the skimmer. Just have a DSB and some rock.
If you are skipping the rock and sand (why would you do that?) then I would suggest the skimmer.
3 fish in a 15 might be overcrowded, depends on what you are planing to keep.
If you are planning a sump you might want to add some macro algae. I would avoid adding them to the regular tank since they might overtake it.
I'm not too familar with the Eclipse but if I remember correctly they have a wet-dry filter. If you could disable that you might be better. They seem to just add nitrate to the water. Although with a DSB maybe you won't have a problem. Try it, worse comes to worse if your nitrate readings are high you can disable the wet dry portion.
Good luck