Hi, I was working for one contract (8 months) on one ship during 2011 - 2012 as a photographer. Nothing much changed since then but life varies from ship to ship (money, atmosphere etc). So, I can just talk from my experience (altough I am still in touch with many people who continued to work on cruiseship).

1. For me, it was pretty good. It was ship with around 1000 workers if I remember correctly and all people were nice, we were like a family. Of course, you choose who are you going to hang out with but many people helped me when I needed help and I helped them besides never saying to each other more than "hi". There were also romances, some people broke up, some people got married.
2. Hmm, there are a lot actually... We live in lower decks (floors) of the ship (yeah, many guests are not aware of this) and we have our own bars, places to smoke, eat etc. Also, if you are going to cruiseship make sure that you don't have breakable things in luggage, they are not treated very well during embarkation and disembarkation, trust me.
3. Southeast Europe (I would rather give no more details, you know, just in case), worked for 8 months then I quit because of personal things... And I think cruiseship industry is like a modern slavery but that's just me.
4. Shitty. I was getting from 1000 - 1100 USD per month but was offered couple of hundreds more. Even in my ruined home country as a photographer I can get that money in about 2 - 3 days. The thing is: not many people here are willing to pay proper prices for skilled creative professionals in my country so incomes are not coming every month. And on ship you always get your money after end of the cruise. Good thing about ship is that you don't pay rent and don't pay for food which is shitty and everyday same but hey, you gotta eat something. So you only buy alcohol, cigarettes, souvenirs or whatever floats your boat - pun intended. :) Some proffessions get more money some less. Just to note: usually on first contract your company will put you on a shitty ship so you have to prove yourself. If you are willing to work for multiple years onboard you can get some nice money but also you will have to sacrifice many things.

5. Hmm, there are a lot of them, some of them are better not to be told. :) Here's the one: on a formal night (all passengers wear tuxedos and expensive dresses and stuff like that, tripping like we are on Titanic) we as a photographers go to a restaurant to take pictures of people. That day is very chaotic, we work very long hours and there is no time to lose. So, with a table of 10 people you get to have a feeling who is with whom (like couples, married). So I am shooting this table with 10+ people, at first glance it's like man woman man woman man woman... So i figured out who is first couple and then just started shooting, throwing some jokes, making a good atmosphere. At the end there is a guy in let's say 40s, maybe early 50s with two ladies on both sides. But there is no one more guy to make a couple. One lady looks to me a bit older to be guy's wife, other lady looks fine, maybe a bit younger. So I just thought older lady is a mother or something. I tell the guy and younger lady to pose for me and older lady starts panicking and crying while everybody is laughing. What happened? I actually told father and daughter to pose for me as a couple while leaving wife out. It was also funny to me but when you are working under pressure (no time to lose) and you are trying to satisfy every guest's needs I couldn't just laugh... I made an awkward face, said I was sorry and offered to make a proper photo. She refused, complaining how her holiday is ruined. I just shrugged, apologized and continued with other tables. :)

   If there is anything else that you are interested in, let me know!