I think eleet is right. This sounds like a lot of time and money to find out the factory and after market stuff is adequate for nearly every need. Industrial plc probes can do lots for you and some of them are relatively cheap. But you need a plc. IR sensors for the brakes would work, you would have to mount them to something cushioned as most cannot take the pounding of a moving suspension. In flow sensors can be done as well - tranny cooler and oil coolers externally mounted. But back to my initial statement - get tranny coolers and oil coolers that have the biggest cores possible for max cooling if that is what you need. Bolt on a thermistor controlled fan if you want. Brake rotors with cross drillings and good design vents do wonders. You can also add ducting to pass more air over them. Or follow NASCAR and actually have a fan blow even more on them - although with those guys, if you can't get enough air moving over your brakes at 180 mph, well.......

Bottom line, you can get all the cooling you want with after market stuff. If the geek in you wants readouts, then you will have to spend real money. Personally, I do not see the benefit of knowing oil temps are 100F below breakdown point for a non race car....And for brakes, the pads and rotors are not usually the problem with brake fade when hot. The fluid is boiling. Use high end racer's fluid and you will get a big surprise in that category.