Do I need to worry about how much data I use with the EasyTether app? Anything else to worry about while running this app?
Well verizon does not officially support tethering on the Droid but I am not sure how they police something like this.
I have not heard of anyone getting hammered for tethering but as always use at your own risk.
So far easy tether works great for me.
I'm sure that few folks actually read their service agreements with Verizon, but you should understand that it is written in such a way that Verizon is more or less free to discontinue service to your phone for virtually any reason they deem sufficient. If they determine that you are using the phone in a manner proscribed by the service agreement you have little room to argue. You can pay an additional fee that they "suggest," or you can give up your service.
That being said, however, purely through my own observation on forums the only people who have actually been caught at this time have been people who have used substantially large amounts of data while tethering. Surprisingly, online gaming does not use that large of data. For example I was just testing out my laptop during a storm with World of Warcraft and only used ~1mb of data in about 5 minutes of playing.
As long as you are just occasionally surfing the web/casually checking email, etc you should be fine. Its when large downloads come into play that you increase the chance to raise a "red flag" on your account.
I don't want to put you at ease with this though, as you use it at your own risk. it is against your tos.