Custom mob spawn for custom dimension 1.19.2

Hi everyone, so I would like to modify the mobs that spawn in a specific dimension modifying the biome file. The dimension is a custom dimension, and is exactly like the overworld, so I took the same dimension file and same noise settings, but i would need to change the mobs that spawn in this dimension. I know that i should modify the biomes file, here a few questions : 

I need to create a new biome file and modify the name in the dimension json? So i have to substitute all of them? There is not other way? 
if i need to modify all the biomes , is there a place where i can download all of them? 
What about the villages and structures generation? Since i will create new biomes i would need to "tag" the new biome to the old one? I dont have any clue with this last thing xD