Do I have cellular line for Apple Watch

Only if you'd like to be able to use your watch without having your paired iPhone with you. If you don't mind always having your iPhone with you for your watch to work, then no, you don't need to pay for a cellular connection.

No, you don’t when you buy an Apple Watch Cellier is optional you can get just a GPS version or cellular(cellular is more expensive) you will have to have your phone and Bluetooth range in order to receive calls and messages etc.