1) Annectens.
2) Absolutely nothing. After it reached 3' in length not even the wood and rocks were safe. He would bite everything in sight the instant he smelled food and just start chewing once he bit the right thing. Hence his name, "Chomp". (Surprisingly, if I didn't have food in the tank, I could lift and move him with my hands, even pet the top of his head with no fear.)
3) a 55 until it reached 35 inches, then pond.