HOW high up in the air? Are you personally more than 128 blocks higher than ground level? If not, then yeah, you may need to move the farm or your AFK spot for using it higher off the ground, or else light up any near-subsurface caverns.
If you are high enough up in the air you shouldn't need to light up anything below. Is your AFK position more than 128 blocks above the ground?
It is the server render distance that matters, not yours, so check if the server render distance is 10 or more.
Spawn chunks shouldn't matter. There is no real advantage to building a general mob spawner in spawn chunks, because they are only active when you are nearby, but it also shouldn't negatively impact the farm. As long as you are within that 24-128 block range it should work.