Once you have the game unpacked, you can use KKManager for updating and you can choose what to update, it looks like this, where you can see, what's using the most space:
View attachment 4389111
You can browse the mods that are included here:
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and get bthe downloads here:
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Animations:
For studio, you probably need a tutorial and a lot of practice to do (smooth) animations. Changing existing or adding new animations is not easy or better: I don't know how and the lack of added new ones suggests, that there isn't an easy way. In the past years, I only saw one mod, that imported animations from Room Girl to HS2 as available animations (in game) and that includes, changing game files, not only adding a zipmod.