Definitely remove the fire dragon, as a rule of thumb never use a single copy of any unit that doesn't have an positive (aka non-blitz soldier) open skill, close skill, or an ability that will send itself to the cemetery.
Also don't forget, Salamander with his 3 range and 30 ATK is one of the few level 1s open skill units in the game WORTH reviving. His open skill is nice, but if you need his field presence or your wordied about your LP, its not necessarily a bad play to revive him. Knowing when to let him die and when to keep him around is one of the things that seperates the best gowen players from the average ones.
So yeah, if you have an extra Salamander I do think he's worth replacing fire dragon.
The bunnies of Lavato have special abilities, like 'Action Skill: Make Carrot Disappear.'