Alas I arrive at work and of course I can't see the pics.
As far as "thermal probes" for your chiller- go with this:
http://www.radioshack.com....jsp?productId=2049773 
its $20 at ANY radio shack -comes with batteries- and does the additional function of telling you the humidity. You can fully submerge the probe that has I would guess over a 6' length of cord?
Now you have some choices. What do you plan on doing with this chiller? First thing to consider is do you want to unleash the beast and go balls out? or do you want it to be a "chiller". If you just want a chiller that will cool water just above the dew point then you will make your life much easier-but you wont get the -30°C that your AC is capable of doing.
Second, See anything frosting? INSULATE IT. the cap tube (the tiny coil of line thats frosting) and everything. That will keep the cold in the cooler, and not dissipating elsewhere. You can get regular "insulating pipe tape" at a home depot/lowes for that. The sticky kind will help to get it stuck to the top of the compressor & all the other places the frost.
Your cooler will work, but keep in mind if its over 20 years old I am guessing that insulating technology has improved so if you get yourself a new fancy cooler it may hold temps better. I have actually had condensation on the sides of my cooler because the 12 can is just not ment to hold -30° just ice and soda.
We can walk you through the CPU block insulation part when the time comes because everything will be different. The sticky tape makes a good seal, but we have better (and far less messy methods) now that we have been doing this for a while.
btw-you have a PM
