Check the literature for the tour part of your cruise to see if all meals are included, or if you pay for some during the duration of the inland tour.
As for the cruise, extra costs usually include alcoholic drinks, soft drinks (sodas, etc), gratuities, shore excursions, items you buy in the ship's stores, photographs, etc. If there are specialty restaurants onboard the ship, there may be a cover charge for those.
Cancellation insurance, which is purchased in advance, is extra and optional. Be clear whether airfare is included in the price quoted to you.