I'm afraid I know more about this topic than I ever cared to.  

The disease has plagued my family since the civil war.  My grandfather was interned in a sanatorium and later I was diagnosed as a possible.

It's caused by a microbacterium very similar to pink eye.  Due to it's very small size, it's easily communicable via sneezing etc.  Most people these days get exposed in pubic and don't know it till they get a cough that won't go away.  Supermarkets are suspected as being the number one place for transmittal since there is such a mixture of people especially from third world countries or Mexico.

The most common test is a skin test, however this is a imune system test that looks for antibodies so a positive doesn't necessarily mean you have it but may mean you have been exposed.  It's hard to grow in a lab and even cultures are only 50% acurate so the skin test is still the best bet.  

It's a hard bug to kill.  The treatment is a drug called INH which is a horse pill you must eat once a day without miss for a year.  Good news is that once you have had the treatment you need never worry about catching it again.  Downside is as a drug it is hard on the liver.  

If exposed or think you are exposed a skin test should be done.  If the person is in your family then precautions have to be taken such as masks, separate laundry, etc and each family member should be skin tested regularly.  Typically this is once a month, however too many tests and this varies by individual and you will test positive exposed or not.  Once you test positive you will always test positive.  As for how commicable, it is really dependent on your suseptability.  Using proper care, my grandfather lived at home in a family of 8 and no one caught the disease and this was before INH.  My exposure was either a baby I held that was diagnosed or just too damn many skin tests as a kid so I had to take INH.  

The other test for TB is a chest Xray looking for spots.  Positive here with a positive skin test is typically considered a hard diagnosis even without a positive culture.  

Not the scourge it once was it is still one major pain in the ass.

You have any personal or specific questions, IM me.

Tj