Exactly what does this do and what if you increase it from 20-80 to say 20-100

It sets the minimum and maximum amounts that your salary cap can increase in a given year (mulitplied by $100K). So, changing it to 20/100 would mean that your cap will increase by a minimum of $2,000,000, and by a maximum of $10,000,000.

This hasn't been mentioned yet, but I beleive that if you make changes mid-career, it takes until the expiration of the current TV contract to take affect.

I wanted to freeze mine at 200 million, but had to settle for 200.8