No. You only need to do deck calibration when you first set up your OT-2, or after it's been moved.
Yes. You must calibrate your pipette every time you run a protocol. It is quick and easy.
Labware calibration is saved across protocol runs and uploads, even if the protocols are different. If you skip calibrating a labware, your OT-2 will use the last calibration for that labware that was completed.
So, if you're keeping the exact same labware setup, and you haven't handled any of the labware, then no, you don't need to redo labware calibration. If you have handled or repositioned labware, you should do labware calibration before running a protocol.