Yep.. You are right though, the 3rd is a nitrogen-cooled CPU
ventilator, it incorporates the same cooling technology of an
aircon, the copper pipes you see are the condensing pipes that
circulates the nitrogen gas and the front unit is the mini
circulator control pump.
Me had a same encounter as you, my P3 CPU fan die on me and the
overheating of the processor would hang the PC while running cos
the floating point of the processing core in the processor is very
sensitive to high temperature, and when running multiple
applications increase the temperature as the processor core works
even harder. After me changed the fan, it was more stable and more
or less back to normal operations.
As the CMOS battery, in an ideal and normal usage, it should last
about 5 years, but there are some hardware theories saying we
should change the battery every 3 years.
My 4 cents thoughts, hope it helps to you. 
