For the mini-bosses, they are supposed to behave that way. Ideally, we want theses to teach you to use the power punch effectively.
Calling them mini-bosses is a bit of stretch. They are essentially souped up versions of enemies that you will be able to find in the overworld once you beat them for the first time.
I am going to deploy an update soon where you'll be able to find more Punch Shrimps in Zennia and Meteo (The 1st and 2nd zone). It was our original plan, but it was cut due to wanting to release the game for Halloween.
For the second point, that feature is already added :o