
In order:
1) Dragoons serve Ishgard as an elite dragon-killing unit. One becomes a part of the faction by presenting a dragon scale of a dragon they killed or helped to kill and Ishgard acknowledging them.
At the tippy-top of the chain is the Azure Dragoon, and he's basically a once-per-generation Chosen One.
2) There does not appear to be anything that would stop you from being a dragoon if you chose to quit, but we don't know how it would actually work at this juncture.
3) The Dragonsong War lasted over a thousand years, so it's safe to assume that Dragoons came into existence purely as a weapon during that time. The first Azure Dragoon became one by tearing out the eye of a powerful dragon, so the war had already begun before he existed. I don't recall if he was credited as a dragoon prior to that, I believe he was "just" a soldier.
Being a Dragoon and having access to their jumpy powers and dragon-killing training is definitely Ishgardian by design, but the Wood Wailers in Gridania also make proficient use of lances.
1) Dragoons serve Ishgard as an elite dragon-killing unit. One becomes a part of the faction by presenting a dragon scale of a dragon they killed or helped to kill and Ishgard acknowledging them.
At the tippy-top of the chain is the Azure Dragoon, and he's basically a once-per-generation Chosen One.
2) There does not appear to be anything that would stop you from being a dragoon if you chose to quit, but we don't know how it would actually work at this juncture.
3) The Dragonsong War lasted over a thousand years, so it's safe to assume that Dragoons came into existence purely as a weapon during that time. The first Azure Dragoon became one by tearing out the eye of a powerful dragon, so the war had already begun before he existed. I don't recall if he was credited as a dragoon prior to that, I believe he was "just" a soldier.
Being a Dragoon and having access to their jumpy powers and dragon-killing training is definitely Ishgardian by design, but the Wood Wailers in Gridania also make proficient use of lances.