Lavi, Bookman and Chaoji had run into Fiddler in an earlier chapter, and presumably there was a fight. Lavi and Bookman were kidnapped by the Noahs, and Lavi in particular is being used as a hostage against Bookman, whom Cyril is trying to gain information from. Earlier on, it seems that Fiddler infected Lavi (and Chaoji, although he was left behind) with some sort of special parasite that's part of his Noah powers.

There's no actual proof that Kanda is dead. If he did die, we weren't shown it. However, Hoshino has said something suggesting that Kanda's going to reappear in the story later. So chances are he didn't die, but it's anyone's guess when he'll return.

For the main enemy, you'll have to use your own judgement, though. There are a lot of different sides to the war in DGM, and most of them have their hands dirty in some way.