Yeah a bit, that was the overflow bottle, which runs from the rad to the back of the bike if it is still there. I would drain flush & replace the coolant. Keep note, if it forces fluid out again in normal conditions chances are the head gasket is blown & is pressurising the cooling system forcing it out past the rad cap.
Repack that silencer. The brakes should be cleaned & pads inspected. Chain/sprocket, tires obviously.
When I bought my 91 it was a total nail, you have to expect that after 10+ years being thrashed in the dirt. Buy a manual. Every so often take things apart & inspect the brgs, regrease them & reassemble, start with the rear suspension linkage which is always suspect, the wheel brgs, steering head bearings.
Also when you are brave it is time to take the barrel off & clean the power valves which will be seized up & maybe the gears stripped (LHS usual). Maybe time to throw in a new set of rings.
The fork & shock oil are due for replacement (though take the shock to someone).
Don’t despair. This is all easy work & will result in a bike that is crisp & handles better than you imagined & you will learn a stack about your bike in the process.
If you haven’t already check out the just kdx site.