A:AnswerMake sure you've selected the correct watch (cellular +GPS) in store/online, but from there it depends on your carrier if your watch is cellular outside of just pairing with your phone. I checked online and asked an employee in store to double check.
A:AnswerIt costed $10 a month to add on my plan but I am not sure if the area or the type of plan you have with them will make a difference in what they charge you. Best thing to do is call and ask.
A:AnswerIt boils down to if it has cellular built into the watch the one that's cheaper normally does not have the cellular service built into the watch so you have to be within proximity of a phone to use the apps where is the more expensive one you don't need your phone on you to answer messages answer the phone so on and so forth
A:AnswerIt works well with all large carriers. Super in case you leave you phone on your desk for lunch and while you are eating. Your Apple Watch will be great.