Ok for one you will not need a valvebody.
The result of the chip is
1. Better fuel economy
2. Better Performance
3. Over all a better running engine
If you run a chip you do need at least gauges. It really is your decission for getting an intake and exhaust. But those are not really needed to run the chip.
The gauges allow you to monitor how your engine is running. They let you see your exhaust gas temp, boost, trans temp, and if you want you can add even more gauges.
Now I have been running my chip since I had about 90,000 miles on my truck. So that is 83,000 miles on my truck with the chip. What problems have I had, transmission was the first. But with a solid rebuild I have not had any problems. I had one injector fail around 172,000 miles but that could have happened even with out the chip.