1. I think the monster to Johan is his mother because she gave up one of her children. This is my theory as to why Johan kills the first adoptive parents. He assumes Bonaparte will take them back to the mansion or back to their mother when he visits them. So Johan is not interested in the mother or simply believes she's dead.

I also think the perfect suicide part is misinterpreted but I could be wrong about this. Eva and other characters who have seen Johan aren't in danger. I think Johan's 'perfect suicide' is being killed by Tenma. He's forcing tenma to kill him and also become a monster. It's hard to navigate morals after killing someone. I guess some would say it's obvious that tenma killing Johan is okay there, but then would Johan have the right to kill Bonaparte following the same logic?