Anthrax is a gram-positive bacterium, Bacillus anthracis, that produces a toxin, which is what kills you. The reason they are so problematic, is they have the ability to form spores, which protect their genetic material, and last for a very long time. Most of the time, if you have a cutaneous infection (infected through a cut in the skin), then antibiotics will work just fine. However, the other two types of infection, gastrointestinal and respiratory, are usually fatal.
I don't know if there is a cure, but there is an anthrax vaccine. The soldiers had to get one before they went to Iraq.
Ya anthrax kill through toxicity. If usually lives in soil though. If I remember the hot zone right one gram per cubic meter of air is about 100% inhalation infection rate.
