With Kai'sa, I think she has great potential for farming now, but her dueling potential in lane can be pretty alright. I think at least one change that could help her out is:
Icathian Rain: Prioritizes targets based on plasma stacks. Each plasma stack throws one more missile at the enemy champion, but dealing significantly less damage with each missile, since at base they do 45 base damage at rank 1 or something. I think just throwing out q in a lane while dueling is just not worth it. And it can help in team fights as you can focus a champion down instead of the missiles dealing damage to the whole team.