Is there any way to make NPC wear nothing? and what character else can use dick growth skills to? Thanks!
Outside of special cases like cutscenes, no. Lust Doll themselves is the only one who's okay with being nude in public.
As for dicks, Alissa is the only person you can grow one on outside the private dungeon. Inside it, there's (so far) also Fawn and Rinny.
Not yet, but there's something in the works!