Fluttering over the water is good practice fluttering. The sheep crab blocking the tunnel can either be damage boosted through, or killed with 3 egg shots. For the boss, you generally won't be hit while standing in the middle. However, the boss dies in ~7 egg shots if you ricochet them up into the side of the uvula. Do this rather than throwing eggs straight up at the bottom of the uvula, which takes many more egg shots to kill the boss. It is possible to kill the boss in 6 shots by shooting at the middle of the sides of the uvula, "slide down the side, aim 2 frames and shoot".