1 - I will think about this as it could be cool.
2 - There already is a new horn in the game that is not the same as the 0.3.5B version of this game.
3 - There were game modes planned but I scrapped them and put all the old game modes into just a survival mode, but I plan to add game modes later. It won't just be survival.
4 - Flying Machines spawn on day 4 and only one per cylinder so in total 3 Flying Machines spawn.
Also about endless mode. It has been removed currently but will most likely be readded later.