Hi @dalec and welcome to the community๐ค. You don't have to purchase boosters to pass any level. I have never spent a dime on a king game and have always moved forward. Sometimes it has taken me like longer than I like but it just makes it that much sweeter when I do pass. They also have contest on the forum where you can participate and win free gold and boosters. It's under the name the fun area under the discussions tabs . Hope this helps and nice to meet you ๐ค
I open the game now once a day to see if quests are back. If not and Toffee remains I close the game without playing. I used to play for hours and even spent a bit of money but will no longer do so. I will not support a game that is no longer interesting and fun.