Yes, people have the right to live or die as they choose. At the end of the metaphorical day, all you truly own is yourself. At the same time, anyone feeling the need or urge to die may be best served by seeking professional help before settling on a decision.
Yes, in certain cases. Just last year my dad died from terrible lung cancer. While he never said he wished he could end it sooner, in a way it was a relief when he passed. When you're terminal and in agony, why not?
Yes, I believe that people have the right to do with their life what they wish, as long as it does not harm others. So, an individual who has a family would need to discuss with and consider the wishes of their family as well when they are making a decision.
Opinions about whether people have the right to end their lives will be hotly debated till the end of time. Personally, I believe that they do with the input of their physicians.