is it healthier and/or spiritually "better" for someone to eat only a little meat or no meat? Can you rank the order of fish, chicken, turkey, and beef/other when answering this question? What is the Ideal amount someone should eat? thanks

There is no halacha regarding these issues. In general, one should eat as healthily as possible, which may also be subjective, so ask your doctor. Spiritually, Rav Kook writes extensively on how the world was originally vegetarian until the Flood, and how the future and ideal world will return to that stage. Whether a particular individual is ready for that stage, and can be sure it does not come at the expense of other issues, see my lecture at: https://www.yeshiva.co/midrash/18137 and then: https://www.yeshiva.co/midrash/18252. Fish is clearly a lower form of life than animals, so they are morally preferred, and as far as I know, doctors recommend fish as well, as healthier.