In relation to tipping, you only tip your cabin steward, waiter and wine waiter usually, but you could tip any member of staff if they give over and above what is expected of them. You dont have to tip bar staff etc as a service charge is already added to the prices.
Usually 15% but many ships can deduct this charge at the time of booking or add it to your on board account as ships are a cash less society. The usual people this covers is you stateroom attendant; waiter/assistant in the main restuarant; Maitre de and the housekeeper. When you buy a drink in the bar the tip is included. However if you get bad service you don't have to tip after all you won't likely see the staff again but they do rely on their tips as wages are not high, but it is true they don't get off the ship that often to spend money so most send some or all back home to their families.
According to Fred Olsen's own recommendation, allow £2.00 per day for your cabin steward/ess and waiter. You can of course give more if you want. On the second last day of the cruise you can pick up small 'gratuity' envelopes from the reception onboard the ship you're on. Hope that helps.