If its the Oceanic biocube, thats the perfect starter tank. You shouldnt need a chiller unless its in a hot part of the house. You can also take out the media thats in the sump area, that way you get more water volume and thus more stability, the biological benefits the media offers is what your live rock will do naturally. You also probably wont need a heater, the pumps and lights will do that for you, but having one is a good idea just in case.
You can really do any small, peaceful fish (ocellaris/percula clowns, small gobys/shrimp goby pairs, cardinals, coral beauty angles, pygmy angles, chromis, and a bunch of others i cant think of; STAY AWAY from damsels though, they set up territories that can be the entire tank (granted there are some exceptions, ie. Allen's damsels are very nice with conspecifics), also purple pseudochromis and royal garamas can be asses in a tank that size. If you absolutely have to you can try an anemone, we had a sebae in our stores Nano cube a few years ago that took over half the tank, so i wouldnt recommend it.
Good luck on the set up! Youll love the tank in a few months once it settles in!
On a side note: t-5's are not good enough lights to have on a tank as deep as a 29. they loose their effectivness halfway down, so any corals on the bottom are going to slowly starve. Power compacts are the better choice, even though they might be more expensive, you will be able to use the entire tank.