1) How it looks.
1a) Also, you will change how the brakes feel under your foot. The size of the master cylinder plunger and the volume of the pistons in the calipers provide a specific "ratio" that you can think of mechanical leverage. With more pistons, your foot needs to travel a little bit farther, but push a little bit less hard for the same braking.
1b) You are correct regarding the benefit of handling the heat - and it is the pad size more than the caliper. The pad creates the friction and together with the rotor must tolerate the heat. A larger pad will run cooler, last longer, and in theory perform more consistently than a small pad. Heat into the caliper is also what happens, but actually a small cast steel caliper will do better than a larger aluminum one because of heat transfer properties.
1c) With any aftermarket calipers, you could in theory adjust the front-rear bias to a proportion that you like the best. That's if you disable the ABS.
2) I don't think the liability police would allow an easy way to turn ABS off. Pulling the fuse will do it. On an '02 I think you are safe in that it won't affect anything else. On newer cars, such as my super-nanny Charger, the ABS and the electronic stupidity control are combined and you turn off more than one thing.
By disabling the ABS, the 43mm rear brakes may (or may not) be slightly too large for front to rear balance and you may (or not) experience rear brake lock-up. Calculations predict it will be very close. I would be very interested in your experience if you try this. Yes, it means a four piston rear caliper is fundamentally too large, and consequently an adjustable proportioning valve is needed to reduce the rear brake line pressure.
Stoptech has some very good, understandable technical articles about brakes, ABS, and more. There is some valuable information there.
http://www.stoptech.com/tech_info/tech_white_papers.shtml
