Yes, the DLC trophies do count for 100% trophy completion of GTA IV. However you only need to get all GTA IV trophies to receive the platinum trophy, but you would only end up with 82% trophies if you don't have the DLC trophies. I am currently on the 82% GTA IV trophy completion because I've yet to play the DLC games. Also I TOTALLY agree with you that there should be no games with online trophies, so many things could go wrong online, such as this god **bleep** Auf Wiedersehen Petrovic trophy, I had to do 2 complete runs of the multiplayer variations to get this "platinum-like" bronze trophy, just because Rockstar failed to make reliable servers to count your **bleep** wins and choke out the "ghost wins" that so many AWP hunters had to hunt down after they've won all multiplayer variations. Well, at least I finally have the platinum trophy now.