Signs of end of life?

Varies. In a "natural" death- in the last few months / weeks - progressive wt loss, anorexia, refusal to eat, weakness, increased sleeping and somnolence, confusion. In the last few days / hours - decreased respiration and altered patterns of breathing, gurgling / inability to handle secretions.
Check hospice sites. Some hospice sites give guidance on the dying process. Quick search found this site: http://www.Hospicefoundation.Org/deathsigns.