The u4ia - Season 1 - in-game walkthrough will guide you through all the choices in the game, with hints of when to check your phone, activate bonus scenes, find collectables, and open galleries. 

The Walkthrough also contains additional renders, animations, and scenes deemed not good enough for the final cut, and a developer commentary with goofs, mishaps, and explanations for some of the scenes and events in the game.

The DLC also contains additional tools, like relationship togglers, money-cheats, and maximizing stats.

The different DLC features can be accessed by pressing F9 at any screen in the game, where you can toggle the different features on/off, and change stats.