I've never been on one.
1. Are there any expenses incurred that aren't included in the cruise price?
Anything drinkable other than water, milk, or drip coffee is extra. Some cruise lines have a "soft drink" pass that either give you unlimited soft drinks or is a punch card. A few cruise lines include everything drinkable in the basic price, including alcohol.
There are extra service items, such as the spa. Pools, etc. are free, but you might have to pay a charge for the sauna.
Most ships seem to have "fancy" restaurants that have a surcharge. You might see some different cuts of meat or some specialties, but most of the rest of the meal comes from the regular dining rooms.
Depending on your room, you will probably have a small refrigerator. I load up on soft drinks (and snacks) at the port stops, and hence only need to buy a soda if I'm sitting in one of the lounges.
They take a lot of pictures around the boat, and boarding the boat, and unboarding the boat, and standing by signs BY the boat. These are available for purchase, later, but they don't record your name so they can't bug you to buy. They post the photos in the gallery and you can find your own and decide whether to buy. Yes, they ARE pricey. But my wife and I usually get our pictures taken for formal night so we have nice portraits.
2. I've heard they're all you can eat, but I'm the kind of person who eats to live vs lives to eat. Any delis where I could just grab a quick bite in 2-3 minutes?
I'm not a shovel-it-down person, either. Most cruise ships have burger and/or pizza stands, and the makings for deli stuff are often left in the buffet line so you can do your own.
There are usually four ways to eat on the ships.
1. There's the fancy, extra-charge restaurants.
2. There's the standard dining room. This is like a typical upscale restaurant, with the waitstaff seating you and handing you a menu. The menu will have some specialties of the day (such as Beef Wellington, etc.) but will have some normal standards (steak, prime rib, etc.) that they offer every day.
If you don't like the entree you picked...or are still hungry...you can get another one.
Seating varies by cruise line, and which plan you select. You can make a reservation for however many, you can just show up and ask for a table. Or you can get the deal where you are assigned to a given table every night, and meet the same people.
3. There's the buffet line, which is what most people talk about. Depending on the line, there may be food 24 hours a day...or you just grab a coffee, dessert, etc. on the way by. There's no cashier, of course, so you can just find the section of the buffet line that has the kind of food you want and stoke up. Often, you'll find the same things on the buffet line that were the special in the dining room.
4. And, like I mentioned, there are the little burger and pizza places. The ships now have espresso stands (often a Starbucks or similar chain). You have to pay for what you get there, but they often have doughnuts, etc. as well as the coffee drinks.
Finally, of course, there's room service. You can also often get light food in some of the bars.
3. How long does it take to board/unboard? That's a lot of people and I don't know that I'd want to spend all day waiting in line. I'm not what you'd call a patient person when it comes to things like that.
Boarding is like a really serious day at the airport. It may take 20 minutes or so to make it through. The cruise lines' customers are generally well-to-do folks who won't be repeat customers if the boarding hassles are too long. I've been in some lines where they have buskers disguised as maintenance people, magicians walking around, etc.
Unboarding is actually a bit easier. You're assigned a time (typically by a color code or group number) and just stroll off the ship at the proper time. However, you usually have to go through Customs.
4. Anything else I'd want to know?
You don't have to haul your luggage aboard the ship...when you check in, they put tags on it, and it's delivered to your cabin, later. However, it might be several hours, so bring a small carryon with chargers, medicines, etc.
It's a similar process disembarking. They give you tags, and you actually set your luggage out in the hallway before midnight. You disembark into a warehouse with the luggage arranged by your group number or color. Grab your suitcase, and head to customs.
But you will need your overnight bag to carry out what you'd used overnight.
BTW, I've never had a long customs wait off a cruise ship....
The nightly shows on cruise ships are a cliche, but they're usually better than anything else going on. Don't expect much, and you will probably enjoy yourself. Sometimes, though, you get a pretty big name cadging a free cruise by doing a few shows. Saw Jeff Dunham that way.
In any case, try it a couple of nights. Comfortable chairs, for the most part, and of course they serve drinks. Catch the show the first night, and decide from that point whether to keep coming back.
Typically, nice little lounges with piano players, classical trios, jazz, etc.
Otherwise, the entertainment later in the evening is a bit lacking. The commercials show big parties in the bars, but there's a large number of older folks on these ships (depending on the line, of course). Took a two-week trip to Hawaii, and the bars were all dead past 9:30.
Most cruise lines seem to have a "Formal Night" where you'll have to wear a coat and tie to eat in the dining room. Buffet line doesn't care, of course.
Ron Wanttaja