There are definitely some books out there on the benefits of flax. Search on Amazon and you'll come up with some. Probably a shorter pamphlet type of book is all you'll need.
As for how much to get benefits: 1-2 Tbsp a day, but work up to that amount, because adding too much too quickly can cause digestion problems because of the increase in fiber.
Also, it's best to buy whole flax and grind your own (get a 'coffee grinder' that you use just for that purpose, or use something like a Magic Bullet if you have one). Some "flax meals" are not whole flax, but flax with the oils removed. Others, which say "whole ground flax" are from whole seeds, and are second-best to buying whole and grinding yourself, but keep it in the freezer to prolong freshness (flax oil is very unstable, and goes rancid quite quickly).