At least I will be popular for making the most annoying and confusing games haha.
As you and Llorx said, the game lacks tutorial, so it will be included soon
Bonuses are always 2x coins obtained in the level (if it is not working this way, it is a bug) but, again, it is not explained anywhere.
The idea for items, is to be consumables, right now they are auto triggered, but the persistence between levels seems to be a good approach
Thanks!