Others will also post here, but just to give you a quick answer, Oceania’s US website will post fares with and without airfare. You will see one column is “cruise only fare”, and another is “OLife fare w airfare”. The latter includes coach airfare, importantly arriving the day of embarkation and returning home on the day the cruise ends.
A best practice is to arrive in the departure city at least one day in advance of boarding the cruise. For this you will pay a deviation fee of 175 per person. This will buy you the ability to have a voice in which flights you are booked on and you can lock in your airfare much earlier.
Others will post here with much more detailed information. This forum is great for having folks who are very helpful with good information. I just wanted to get back to you quickly .