I can only answer question # 1. Yes, tips can be added to your ship board account. They will give a voucher that you slip into the envelope provided for the amoumt you specified. The crew member will be given that amount when presented.
Just go to the account desk, guest relations or other name that is known (purser, etc) and specify the amounts for for each person, waiter, asst waiter, cabin attendant etc.
However, the Princess Sun class ships do have choices of places to dine. There is an excellent pizzeria and now they have a brand new upscale steakhouse. They also have The Bistro, the Horizon Court's sitdown, menu restaurant. It operates that was between 7:30PM and 4:00AM. So few people ever ate there, I think they didn't know about it, but the food was all cooked to order. It's the only time on a mainline cruiseship that I ever was able to get a piece of salmon cooked rare, which is the way I like it. I loved the food in The Bistro, it was the best on the ship IMHO.There is also live music and a dance floor, a BIG dance floor for the nimble footed among us (not me). You can eat at the pizzeria and The Bistro anytime you want, without reservations. The steakhouse is the only restaurant onboard where you will need reservations. Have a wonderful cruise.
We know about the bistro -- but who wants to skip dinner in the main dining room? The food is outstanding (yes, I know a few snobs will argue the point...) and the waiters in the main dining room are always up to something. It's an act that I don't want to miss!
The Horizon Court's bistro is very popular for what a local Benedictine abbot calls "coffee and..." after the evening entertainment.