1. Everything Jehovah's Witnesses believe is based on the bible. And yes, the Bible says, "abstain from blood" Acts 15:20, so they do not take blood transfusions. Members are not automatically disfellowshipped, disfellowshipping is done when members unrepentantly make a practice of breaking the Bible's commands.
2. Definition of Cult-a small group of people having religious beliefs or practices regarded by others as sinister. Disfellowshipping is based on Bible principles 1 Cor 5:13, and there are over 8 million Jehovah's Witnesses.
3. Members are not left homeless. My father-in-law was disfellowshipped and needed care and my sister-in-law took him in. When someone is disfellowshipped members of the congregation do not SOCIALIZE with them, this is in accord with the Bible's teachings, this doesn't mean they don't take care of family members who can not take care of themselves.
4. If a patient decides to receive blood, that is their decision, and as a nurse, we need to be the patient's advocate.