A Few Questions

[joeymeboy98]

1. Is there any promotional content? (I.E. Anything only available for a limited time or more complicated than just buying DLC)
2. Is there anything permanently missable, even rewards for fulfilling specific conditions?
3. Is this game identical on all platforms, including the Switch version having an in-game achievement system?
4. Are there any bonuses for having save data from a different video game?
5. How difficult is the game to fully complete, and can you still change difficulty on the fly?