Batman Arkham City

[Frankie_Says_Relax]

Somebody throw me a bone here, I'm sick of collecting trophies to finish the Riddle side quest. I noticed that there is one empty upgrade ? in Batman's page that I can't even see yet. Tell me this unlocks at some point and I can start solving riddles with those weight sensitive buttons on walls. Or that some interesting story twist happens that will make it worth this mundanity.

Batman's upgrades aren't tied to any Riddler side quests or trophies.

While there's nothing that allows you to cheat your way through the process of getting the trophies, the Riddler trophy hunt becomes easier (from a locating standpoint) if you track and interrogate Nygma's operatives.

Once you hit a specific point in the game you should get a tutorial showing you that in detective mode Riddler's operatives glow green. Take out every other goon in the group and leave those for last and you'll get the option to "interrogate" them. That will make all the trophies for a specific area light up on your map. It won't help you get them but it will show you where they are and interrogating every last one of his goons is an in-game stat/achievement.

Is the Nightwing/Robin DLC worth it?

It's just the challenge modes/fighting rooms. If you're completely obsessed with the game like me, it's very very cool to play as Robin and Nightwing and try out all of their gadgets, but there's really no stories that accompany those downloads. So, YMMV.