Overall, I like your ideas, but there are some other things I'd like to change.
1. Slobber Shot should be similar to Snapdragon's in which enemies escaping his range can still be vanquished if caught in their secondary's projectile if played properly. Instead of being a sniper-like attack e.g. Electric Slide & Wizard's primary, it should be a projectile like Snapdragon & Engineer. Because sniping at mid-range (assuming the zombie hasn't ran across the map at that point from Chomper) isn't viable, it should act like that instead.
2. There should be an indicator for when a zombie's health is below 50%. Because of the complications of who's above the chomping block & did I deplete him enough, Chomper should have an easier time to know who has that status by simply being close to zombies.