A couple of ideas that might help balance chickens (and just be funny) is if a fireball goes over a chicken it roasts it, spawns 2 valuable chicken legs and no longer spawns more eggs for the round? And perhaps if a fireball goes over ocean, it creates steam, which if it boinks chicken, it lays boiled eggs instead which are worth less as a base but could interact with toast?
Also do you foresee rounds beyond week 7? Maybe you get a new row of slots but money is wiped, call it the greedy tribute or something like that?