The Catholic Church always Requires nutrition and hydration be given, no matter what. That is typically one small tube inserted into the nose, but even if nutrition and water needs to be administered through an iv or a gastro tube, nutrition and water need to be supplied through that method. It is only okay to stop nutrition if it becomes apparent that the body is no longer able to digest nutrition.
Life Support is where a machine is breathing for you. It is acceptable to make the decision to withdraw life support if there is not a possibility of recovery.
The best practice for a Catholic is to not fill out an advanced directive, nor any sort of living will, but rather to appoint a health care representative who is Catholic and also understands what the Catholic Church teaches about end-of-life issues. Indiana has a form titled “Indiana Health Care Representative Appointment” (click HERE to view the form)
Make your funeral plans now and send them to the funeral home, your parish, and any people who you feel like would want a copy of your plans among family and friends. Sometimes, the parent is a faithful Catholic who would clearly want a funeral Mass, but if the children are not practicing, the family may not want a funeral Mass. It is critical to make your funeral plans out ahead of time so that there is no discussion about you having a funeral Mass.
The Catholic Church says the body should be present at the funeral Mass. Cremation is only supposed to happen after the funeral. If cremation is chosen after the funeral, the urn needs to be buried or placed in a vault. It is not acceptable to scatter the ashes, nor is it acceptable to keep them at home, nor any other practice contrary to burying the urn or placing the urn in a mausoleum.
The only situation where cremation is acceptable before the funeral is when the funeral is a great distance away.