Hi
Please don't worry about the pot worms, they aid the composting process and are a valuable member of your wormery community.
Pot worms generally like more acidic soils, but as you state you regulary use egg shells - i expect you are controlling ithe levels well.
I have never heard of potworms starving your compost worms out, and when you empty the trays - dont worry about throwing the potworms into the garden.
Obviously the more food that gets eaten, the more water is produced, often when the worms move away from the lower trays, the drainage passages that they make won't be there, so the lower trays can become soggy.
One of the benefits of vermicompost is the fact that it holds water , so you are seeing this in action.
HTH
Ronnie