It Depends. Propofol is one of the best anesthtics although any medication has its own side effects.
All. Anesthesia has the potential to cause fatal reactions. That is one of the risks you sign for when give anesthesia consent. Proper administration and monitoring can make the risks small with a good anesthesiologist.
Yes. As has been seen in the national media if this drug is used by people not trained in anesthesia it can cause death. The medication causes respiratory depression as well as blood pressure decreases. It should only be used by anesthesia providers who are trained to handle patient's airways, as well as the side effects of this drug. In their hands it is very safe.
Yes. See the tragic death of Michael Jackson. In the right hands (an anesthetic or other trained professional), Propofol (trade name "Diprivan"), and with appropriate monitoring of vital signs, this is a perfectly safe anesthetic drug. Unfortunately, it is too often administered by untrained people who cannot deal effectively with it's well-known side-effects, such as respiratory depression.