Hole in coolant hose/gap in plastic
 

Hi, I am new here and just wanted to ask a question. My car has been overheating for a few weeks now, until I had to park it and drive an alternate car. I checked the hose that the coolant goes through to find it is not hard, but loose and squishy when the car is on. I learned from past experience with another car that that is not a good thing. I can see where coolant is seeping out from the hose and from the actual reservoir. There is also a gapping piece on the motor where there is a black plastic thing on the side taht meets with the motor. I am afraid it should not be that way and is causing issues as wel.

I have a 1995 Mazda with 180k miles. How easy is it to replace that hose and is it an inexpensive fix? Why had the black plastic separated from the engine is that what a engine crack is?