A TA should provide you with the Oceania invoice.
Yes.
SATaxman is correct. These are all included in the cruise fare.
As SATaxman said: yes, only one person has to upgrade.
Yes, the $69.95 price is for people who booked under the old OLife program and did not chose the basic package as the OLife perk. Under SM, your option is to upgrade at $30 pp pd.
When you consider the upgrade, be aware that the package includes gratuity, which is 20% when drinks are ordered ala carte.
Also, there is a daily happy hour in the lounges with 2 for 1 drinks (same drink) from 5 pm to 6 pm, and another in Horizons at 10 or 10:30. In addition there is a Captain's Reception on one night where drinks are free and usually a first-timers reception where they are also free.
Have a great cruise!