1) Since the effects of the cards on top of the burst resolve first, the Canon of Casualty would do damage to Creature 1 before Viper Lash defeats Creature 2. However, I don't know for certain how to handle it from there. Either both creatures are defeated or only Creature 1 is defeated. My guess would be the second one, because Creature 1 gets coded before their attack hits, so the battle ends before damage can be dealt (plus, battles in the show tend to go to whomever died last when both creatures are defeated in the same attack. However, I don't always take the show's word for it on certain rulings for reasons I'll discuss below).
2) The show's rules and the actual game's rules tend to differ in areas, and this is one of them. For instance, the game's rules say you can't have more than two of any card in your deck. But, in the episode "Everything is in Flux," Klay loads up his Location Deck with 10 Lava Ponds (and Codemaster Crellen doesn't appear to object). So, yes, if the Creature isn't destroyed in battle, its Energy is restored to maximum.
In girum imus nocte et consumimur igni
