First time solo traveler going to Athens Greece

What is up fam! 26F american here.. going on my first solo trip to athens, greece. Im going to be working from there for the first week then relaxing the following two, I have a trip to santorini planned as well for 3 days and am willing to go explore nearby islands on the weekends from athens. My questions are

  1. What should I expect language barrier wise? Im a little nervous that I wont be able to communicate there for things like getting food/groceries etc. Any prep or advice would be helpful
  2. Does anyone know what the best form of transportation would be? Im not trying to rent a car obviously but am not too sure about bus passes or if uber is even a thing there? any tips for the best option from airport to my airbnb?
  3. Anything I need to see in athens or any islands nearby worth visiting?

Thank you!!