Antihelium has been observed: http://www.theguardian.com/science/2011/apr/24/antihelium-antimatter-brookhaven (sounds like just the nucleus, not a neutral atom).
The AEgIS experiment http://aegis.web.cern.ch/aegis/research.html plans to make neutral antihydrogen atoms and measure their gravitational acceleration.
Also, when an anti-hydrogen comes into contact with a heavier element (say carbon), are both atoms totally annihilated, or does the heavier element ( of matter) simply reduce by one proton and release the energy?
It wouldn't be possible, e.g., for both atoms to annihilate and produce nothing but gamma rays, because that would violate conservation of lepton number and baryon number. However, the annihilation of the antiproton with a proton will produce an energy of ~1 GeV, which is much more than the binding energy of the carbon nucleus. Therefore the carbon nucleus will likely fly apart as individual neutrons and protons.
In science fiction, antimatter is often portrayed as a way of storing large amounts of energy to run a spaceship. This kind of makes sense, because the energy density is orders of magnitude higher than, e.g., uranium used to fuel a fission reactor. However, it's not necessarily easy to extract the energy for useful purposes:
Antimatter Propulsion System
Would matter-antimatter annihilation create a fireball or not?