Regarding tribe placement:
To my knowledge, there hasn't been any lore presented to us in game or elsewhere regarding where any tribes are settled (or why they settled there). The two tribes that we interact with in their settlements are the U (Drake) and M (Marmot) tribes.Â
It has always been my headcanon that the tribes settle where ever their particular "totem animal" is abundant.
So... for the U tribe, they'd settle near drakes... which, if you look around the desert near enough to them you can find some wild drakes. The M tribe would settle near marmots... which I don't recall seeing any in the Fringes where you run into the tribe, but it makes sense to me that marmots are creatures that are pretty plentiful anywhere.
Again, just headcanon so do with it as you will.
Regarding your personal headcanon for your tribe:
Again, nothing much is stated about tribal traditions and the like for the tribes, as far as I can recall. As such, your headcanon for your tribe seems like it would be fine to me. It's very unique and interesting.
The only issue you may run into is if you end up interacting with another player from the Y tribe that claims La Noscea as their tribal home... that has a completely different idea of how tribal life would've been. Of course, this is a risk with any headcanon, but you get the idea.
Overall, however, go on with your bad self.Â
Regarding white mage/magic:
As you likely already know, right now the only ones allowed to practice white magic are the padjal who were entrusted by the elementals. And of course special snowflake WoL.
As I recall, Koji did mention "other means" to learn white magic, but said they were "nefarious" in nature. Beyond that, we weren't given any details. Granted, I've not done the 60-70 job quests so perhaps more is explained in there....?
Overall, though, what you do with your character is ultimately up to you. I doubt you'll receive the "backlash" you're expecting should you choose the white magic route. There may be pockets that may avoid RP'ing with you simply because they wish to stick to the "only padjal and WoL know it", but that can be true about any sort of RP. It's just a matter of finding that group of roleplayers that think enough like you to allow that sort of RP into their stories.
They're out there, you just gotta find 'em.
Edit to add:
If your only reasoning to wanting to be a WHM is because they're powerful and you worry that the conjurers are weak... you couldn't be farther from the truth. Conjurers are quite powerful by their own rights. Those taught in Gridania tend to stick to the elements that we are given in the game mechanics... however, conjurers are able to conjure spells from the entire elemental wheel. So fire, lightning(thunder), ice, etc. are all within their grasp, as well.
They are still very skilled healers and also very strong combatants, even if you just stick with the Gridanian teachings.
Again, this isn't me saying don't do your white mage business. Just saying to not let the "upgrade" from the conjurer class to the white mage job fool you into thinking one is inherently weak(er).
To my knowledge, there hasn't been any lore presented to us in game or elsewhere regarding where any tribes are settled (or why they settled there). The two tribes that we interact with in their settlements are the U (Drake) and M (Marmot) tribes.Â
It has always been my headcanon that the tribes settle where ever their particular "totem animal" is abundant.
So... for the U tribe, they'd settle near drakes... which, if you look around the desert near enough to them you can find some wild drakes. The M tribe would settle near marmots... which I don't recall seeing any in the Fringes where you run into the tribe, but it makes sense to me that marmots are creatures that are pretty plentiful anywhere.
Again, just headcanon so do with it as you will.
Regarding your personal headcanon for your tribe:
Again, nothing much is stated about tribal traditions and the like for the tribes, as far as I can recall. As such, your headcanon for your tribe seems like it would be fine to me. It's very unique and interesting.
The only issue you may run into is if you end up interacting with another player from the Y tribe that claims La Noscea as their tribal home... that has a completely different idea of how tribal life would've been. Of course, this is a risk with any headcanon, but you get the idea.
Overall, however, go on with your bad self.Â
Regarding white mage/magic:
As you likely already know, right now the only ones allowed to practice white magic are the padjal who were entrusted by the elementals. And of course special snowflake WoL.
As I recall, Koji did mention "other means" to learn white magic, but said they were "nefarious" in nature. Beyond that, we weren't given any details. Granted, I've not done the 60-70 job quests so perhaps more is explained in there....?
Overall, though, what you do with your character is ultimately up to you. I doubt you'll receive the "backlash" you're expecting should you choose the white magic route. There may be pockets that may avoid RP'ing with you simply because they wish to stick to the "only padjal and WoL know it", but that can be true about any sort of RP. It's just a matter of finding that group of roleplayers that think enough like you to allow that sort of RP into their stories.
They're out there, you just gotta find 'em.
Edit to add:
If your only reasoning to wanting to be a WHM is because they're powerful and you worry that the conjurers are weak... you couldn't be farther from the truth. Conjurers are quite powerful by their own rights. Those taught in Gridania tend to stick to the elements that we are given in the game mechanics... however, conjurers are able to conjure spells from the entire elemental wheel. So fire, lightning(thunder), ice, etc. are all within their grasp, as well.
They are still very skilled healers and also very strong combatants, even if you just stick with the Gridanian teachings.
Again, this isn't me saying don't do your white mage business. Just saying to not let the "upgrade" from the conjurer class to the white mage job fool you into thinking one is inherently weak(er).