We took this cruise in November but it was from Hawaii to Ensenda. Hopefully my answers will help.
We got dropped off at the San Diego Airport and saw the next Infinity cruise passengers loading on buses. You meet right outside the Hawaiin Airlines drop-off area. There will be 3-4 buses there to greet and load evereyone. The bus ride to Ensenada is about 3 hours and goes quickly (sit on the right side of the bus for some beautiful scenery!).
The ship has activities for all ages...not to worry. There are computers, fun lectures, cooking lessons, dance lessons various tours, computer classes, photography lessons etc. There are two swimming pools and jacuzzis. Evening activites include casino, lounge and dancing for the adults.
We enjoyed the cruise alot.