Re: significance to testing/belt rank?
The significance will vary from school to school and your rank mostly means nothing outside of your school. Even within an organization, other schools may not recognize ranks from your teacher.
Some organizations will put out a syllabus with minumum requirements. Although they can not be subtracted from, some may add t it
I'm really convinced that all ranks are political in atleast some way. I know very good martial artists with no rank and lesser ones with high ranks. And it's nothing new:
"In 1837 Matsudaira Awaji no Kami Takamoto wrote a blistering commentary on martial arts instructors...
He charged that teachers not only refused promotion to those who have trained hard but also awarded certification to favored students without regard to actual ability. As a consequence, skilled students might lose confidence in their teacher and leave the school." Hurst: Armed Martial Arts Of Japan: Swordmanship and Archery.
This was even before the Kyu/Dan system.
The entire ranking system should just be scrapped and belts of all colors done away with. This will help bring an end to some of the ego, politics and the cash cow that test/certificate fees have become.