The bubonic plague was a painful disease, with black buboes, or swellings, in the groin and armpits, which lasted up to a week. There was some chance of surviving if the buboes burst.
As of 2015, full retirement age is 67 if you were born after 1960. The amount you receive doesn't change because disability benefits were calculated based on what you would receive at retirement age. However, you may see an increase if Social Security provides a cost of living increase.
You can sign up for Social Security as early as age 62, but your benefit will be cut by 25% to 30% compared with what you'd receive at full retirement age. For people born after 1954, full retirement age gradually rises; for those born in 1960 and later, it's age 67.