The third point is the one that gives the document its character as a legal instrument rather than a declaration of goodwill, because it addresses the machinery rather than the doctrine.
A fatwa is a non-binding legal opinion, issued by a qualified jurist in answer to a question. In classical practice the qualification was institutional: a mufti was trained in a school, held a recognised standing, and answered within a methodology his peers could examine. What changed in the twentieth century was distribution. Print, then broadcasting, then the internet made it possible for anyone to issue a ruling to a global audience without any of that apparatus, and for the audience to have no means of telling the difference.
The Amman ruling responds by putting the conditions back on the record, agreed across the schools, so that the question of whether a given pronouncement is a fatwa has an answer that does not depend on who is asked. It does not create an enforcement body and it could not: no institution has jurisdiction over Muslims as such. Its force is the standing of the scholars who signed, which is why the number of endorsements and the range of countries they came from are recited as part of the instrument.
Whether it has changed practice is a matter for observation rather than assertion. The atlas records what the instrument says and who adopted it, and does not measure its reach.