Mini boss mode should start from the beginning i.e. the start - it should be a journey and not start from the level you are currently on, it is useless to grind on it or even use it and had no real impact on the game play.
Trading stock really is a pain, its too slow,, the margins are too small, it needs beefing up with a bigger risk factor rather than just waiting and waiting....
endless, but the ending spirit level can be defeated at like lvl 10ish?