Can you help me with a few really simple ECU upgrade questions?

So i know there are a ton of upgrades for an engine computer but im not sure what they all can do... are there ones that are a upgrade for the computer that replaces or upgrades the existsing ECU and can be calibrated for different driving modes? i mean calibrate like there is a little control screen insode the car where you can select from different shift/power options like eco, gas saver, track, drag, that sort orf thing? the control doesnt even have to be in the car, it sould be in the engine bay too... so, does such a thing exist, and if so how much would it cost, how hard is it to install, and how broad is the range of vehicles they are made for? (cough, 2002 grand am gt, cough) thanks!