please dont go with that skimmer, that isnt really that good, the concast area is not large enough for the skimmer to do much. as for those fish, a 10gal is way to small for 3 fish. i would do the firefish and the clown, the watchman needs more space because they eat on stuff in the water and on the rocks (forgot what its called) the taam nano skimmer doesnt work, i got one and the impeller didnt even run and the whole thing just looked horrible, i recomend spending at least $100 on a skimmer, i got this: http://www.marinedepot.com/AquaC_Nan...AC3431-vi.html
and it is absolutly amazing, it produces so much skimmate and the skimmate is a dark tea color! http://www.marinedepot.com/CPR_SR2_P...ISVSUH-vi.html
this is also a nice skimmer, but its in tank so it might be distracting.
you will also need a hydrometer and a saltwater master test kit, reverse osmosis water and of course a light.
in a 10gal a chocolate chip starfish will get WAY to big for the tank, i would recomend sticking with the shrimp, some hermits, and some snails for your CUC. also i would go a 4-6inch sand bed for biological reasons :P
i hope this helps and i hope you do good on your tank, ill be stopping in to look at this thread often because this seems very interesting.