First of all,
. Both tools (I assume you mean the "Dealertool") will let you balance the throttle bodies, as well as read many of the sensor settings and reset fault codes. Tuneboy will also let you change settings in the mapping tables, however if you're only interested in doing maintenance then the Dealertool would be cheaper and easier to use. KildareMan has one, so he may provide more detailed information for you.
A Tuneboy key is specific to a particular ECU, and doesn't expire.
Neither tool will actually balance the throttlebodies for you, they simply give you a readout to look at while you adjust the setscrews. It's not diffiult to do, but it's fiddly, as you have to remove the tank and the airbox, then hook the tank back temporarily to run the engine while adjusting the screws.
The other thing you will definitely need is the workshop manual.
Hope this helps.