It sounds like you may not be connected to the internet within the app if your EXP is never going up. It starts to rise slowly at higher ranks, but it should always be going up a little!
Features tend to be random. Sometimes you have none and sometimes you have a lot. Ensure your app is connected to the internet properly and then the best you can do is just keep clearing levels. Good luck!
This may be because your app is not connecting to the internet. Try signing out and back into your account. In the worst case, you may have to reinstall the app but you will lose all boosters and unsaved progress
levels are usually stored on your King account so by signing into your email it should restore them. Do you have any other email addresses your levels may be stored to?