Your final three questions:
Should the supplementary Q&A sheet considered as legimate official definitions, or should it be considered as a one way of interpreting the Resolution B5?
That supplementary Q&A absolutely should not be considered as legitimate official definitions. That Q&A pertains to the original draft of the resolution. The final, voted-upon version represents a significant departure from the original. The final version added the dynamicists' concept of "clearing the neighborhood" to the definition of a planet, and the concept of double planets is gone. The IAU currently deems Pluto to be a dwarf planet, but not Charon (but that may change). From https://www.iau.org/public/themes/pluto/, "For now, Charon is considered just to be Pluto's satellite. The idea that Charon might qualify to be called a dwarf planet in its own right may be considered later."
If the Q&A is legitimate, then why is the definition of the satellite is not included in the Resolution B5? If not, is the official definition of the satellite nonexistent currently?
This question is a bit moot as that Q&A is not legitimate. There is no official definition of what constitutes a satellite. By any sane definition of the concept, Pluto is not a satellite of Charon, so Pluto's status as a dwarf planet is secure. Whether or not Charon is a satellite of Pluto is a matter of debate, and I suspect the IAU has had it's fill with rhetorical debates given the heated objections to their definition of the term "planet".
Are there any source or archive of the official or widely accepted definitions of glossaries in the fields of astronomy?
There is one word that does have an official meaning, and that is "planet". "Satellite"? No. "Star"? No. "Galaxy"? No.
Regarding the debate with your friend that made you ask this question, the only way in which one could view the Moon as a planet is by the fact that its orbit about the Sun is convex. That is a consequence of the gravitational force exerted on the Moon by the Sun is always greater in magnitude than that exerted by the Earth on the Moon. That's not a good definition; the IAU certainly doesn't use it. Along with the Earth's Moon, there are several outer moons of the giant planets that have this same characteristic, and they're all listed as satellites.