Hello, I am college student writing a paper on tuning software. More specifically I am writing a paper on the benefits or draw backs to tuning the every day car. It has been mentioned to me on several occasions that the manufactures deliberately detune vehicles. I have a few questions that I would like to get answered by those that use tuning software on high performance cars.

What brands of software are available for tunes?
What type of Operating system and specs are needed to install?
What type of training is involved to tune a car?

Is it really a benefit to tune the average day driver?
Will that give you better gas mileage and better performance out of the vehicle?
Are there certain vehicles that just can not be tuned?

Any answers are appreciated and welcomed. Thank you for helping me in advance.