No the stairs aren't going to be a bother. While everyone uses them, only large amounts of people use them before and after meals and shows. Late at night, the stairs get more limited use.
You don't need a passport, but I would highly advise one. You will need a photo ID plus an official copy of a birth certificate with a raised seal. However, if there are any problems, such as a suspected terrorist caught on an island, passports are a far better form of national identity than the former. Besides, one will last you ten years and they are very easy to get. I've had passports nonstop since I was 17, and I'm 63 now!
I have to agree, traveling with a valid passport is the best form of identification you can have, especiall since last Sept., with all the tighter security. If you have time before your cruise, I'd go and apply for one, here is all the information:
I'm leaving in a week and do not have any passports. For a family of five, that would have been an additional $200 on top of everything else. I have everybody's original birth certificates, photo IDs, and will make lots of copies so we don't incur any problems. Passports are no doubt more convenient but if you don't travel often, they can be expensive for a larger family.
I have a passport but can't find it and believe it has expired anyway. Last time I needed it was in 1986 but I think I'll probably try to get a new one because it is easier and the big reason is because some super last minute deal might come up for a European cruise and I'll need to be ready to go.
Thanks for the responses.
Laura's point is well-taken on the expense issue, but not having a passport severely limits people to where they CAN go and CAN'T go. And, often, is hasslesome even in the countries that don't require them.
Donna is 100% right on. It's the best ID you can have.