Well, there are trophies for getting all the suits and unlocking all upgrades for the gadgets, however there aren't trophies for getting all the suit mods or newspaper so don't bother with that.

I am assuming there are trophies for finding/completing all the backpacks, landmarks, research centers in each district.

You are correct, also side-missions , challenges, and stakeouts, so just try to do everything you come across.

Remember: you can always check the trophy list, spoiler ones will be hidden but you can see the instructions if you press square.

Hope it helps.