hammers are going to need some decent lighting to stay vibrant and healthy for longer periods of times. Button polyps are very common, mushrooms, and certain lower light leathers are also common in low light setups.
For lights i would get a 24 inch T-5 HO setup. Low cost for running, very low heat, and will grow coral anywhere from mushrooms, to frogspawn, being about the highest in lighting thriving you would want to go.
For filtration i would do a small skilter, hang on filter skimmer combo. Not normally the best thing in the world, but easy to clean and you get a skimmer built right in. I would also recommend a very small fuge. They make them to hang on the back of the tank, and you could add a small light to grow macroalgae to get rid of nitrates/phosphates
I would also recommend about 20 lbs of LR and about 20-30 LBS of LS.
No fish sounds like a good idea. Anemone shrimp (sexy shrimp) skunk cleaner, peppermint would all be good choices. My favorite would be the blood or emperor shirmp. Very nice dark red color. All of these shrimp are also coral friendly. Feeding is very easy for these guys, just a very small pinch of flake with the filters off, so that they can get it off the ground and rocks would be a very easy way to feed.