My technical experience:
1. For clothing, you can use the old method: use multiple color textures for one model. Simply import the clothing texture into Photoshop and adjust the hue.
Then, set a "color judgment" for the NPC to read the corresponding color texture.
However, I don't recommend pre-loading all textures in bulk; instead, the game should only reload the selected textures during "nighttime sleep" and "passing time" scenarios.
2. Yes, several authors I know think this way. Purely erotic content is difficult to survive in today's AI-driven, free-mod environment. Only better storylines and more detailed settings can guarantee the continued development of the game.
3. I just hope that the effort put into each NPC will not be in vain.
4. For now, only weather is needed; weather is only a partial trigger condition. As for issues like wet fur and water stains... I know this is troublesome, which is why I didn't mention wetting the NPCs before.
Keep up the good work.