The hose that was replaced wasn't rubber...it was silver near the front of the car and was $103.46 They said they tested the fan and it's turning on and off at the right temeratures.
Your continuous overheating problem is because there are still air pockets in the system. You have to use the bleeder screw on the pipe that you had replaced to vent the air out of the system (you have to do it carefully too because this screw is fragile). It took me the better part of an evening to get all the air out of mine when I replaced that same pipe (did it myself). When I was done, the car actually ran 5 degrees cooler than it used too.
I can't believe that you've had all of these problems in less than 100,000kms. Mine is at 135,000kms and that coolant pipe was the only thing I ever had to replace. It had a pinhole in the weld of the mounting bracket that's near the exhaust manifold.

I got my pipe at wholesale price for about 85$.
Whoever said that these cars are good for people who work on them themselves is right though. I usually do my own maintenance and repairs (unless I don't have the right tools for the job). This car has been cheap for me.
And the Resale on a 2001 base model Cavalier is about 4,500$ black book value.