Is the supplement l-tyrosine safe to take and have the health benefits reported for this amino acid been experimentally validated?

Unknown and no. As is true for most supplements, there are no good studies that demonstrate any true health benefits to l-tyrosine or other amino acids. Since there are no studies, we also do not know anything about their safety. The best thing is to eat a well balanced diet, avoid excess alcohol or other vices, and exercise.
Yes. But the health benefits exist for many problems, but it should not hurt! should be taken with water on an empty stomach!