I just replaced the radiator in my 97 SL2 today. What exactly are you asking? Step by step instructions?
Make sure nothing is clogged in the block
The plastic tank on the side of the radiator can be replaced but it would be quicker and cheaper to just install a new radiator.
I had a similar problem and ended up replacing both the lines and the radiator.
On my 1992 Saturn the radiator petcock is above the splash guard on the bottom of the radiator on the side closest to the belt. You may want to drain the radiator via the lower hose. The petcock on my Saturn came apart. The retaining clip came off of the back. I did not force it and according to the Saturn forums this happens. I am now trying to see if it can be repaired or replaced and much farther than I wanted to be from completing a quick water pump change.
Search Saturn radiator removal on youtube. Youll see a video by Richpin
The lower radiator hose goes from the bottom of the radiator to the engine block. On the engine side there will be a neck that comes off the block and the radiator hose is attached too it. Inside that neck is the thermostat and it can be replaced as a whole unit (the housing neck) or just the thermostat can be removed and replaced.
If the Chevy Celebrity radiator is smaller that the Saturn radiator it might well overheat from not enough cooling capacity. If the Chevy Celebrity radiator is the same size or larger than the Saturn radiator I would think it would not over heat.
Gas is not getting into the carburetor because no Saturn made ever had one.
Saturn radiators don't have caps to check and add fluid to the radiator you open the overflow tank and add it there
It's only radiator cap is on the coolant reservoir.
It's an aluminum radiator with plastic tanks.