The Black Jack tourney is a little different than playing BJ to win money. At the table playing to win, your only concern is to beat the dealer's hand so you win. In the tourney, you have to do that BUT you also have to beat the other players to win overall. This can lead to doing things you would never consider doing at the table like doubling down on blackjack to make more money so you can beat the other players. This means you have to pay attention to how much money you have versus the other players during the tourney so you can judge how much you should bet so that you can keep up with them or get more than them.
For real casino BJ its pretty simple. You want to be closer to a value of 21 with your cards than the dealer's hand is. Aces are 11 or 1 (and you can change their value as you collect cards) 10's and face cards are 10 points, all the other cards are face value. A BJ is a 10 and an ace. Everyone at the table gets 2 cards the dealer has one of his 2 cards face down. Then every one takes turns trying to get to 21. IF you have a blackjack you win immediately as long at the dealer does not have 21 also. (If they have an Ace of a 10 showing they will check their down card to see if they have BJ) If you don't have a black jack you have the option of Standing pat with what you are dealt (say you have 20) hitting (meaning you draw a card and add it to your value) splitting (only on pairs) meaning you match your bet and the pair of cards is split into 2 hands which are then played one at a time, or doubling down (typically done when you have a total of 10 or 11) where you double your bet and receive one more card. If your play results in you going higher than 21 you "bust" and lose. Once everyone is done taking cards, the dealer exposes the down card and plays by a set of rules, typically, the dealer stays on 17 or higher and hits anything lower. If the dealer busts everyone who didn't already bust wins, if you are closer to 21 than the dealer you win, if you match the dealer, you push and if you are less than the dealer you lose.
There is an optimal strategy for playing based on the card you have and the dealers exposed (up) card. As far as etiquette goes, there is not much other than you are not supposed to touch the cards. The dealer will move them around. If you want to take a hit, tap your finger on the table or knock on it lightly. If you want to stand, wave your hand over your cards. Most dealers know the obvious plays and you can kind of take your queue on what to do based on their action. If they deal you a card and then act as they are moving on to deal to the next player than its a fairly good sign that you should stay because most people play then same.
You can go the first sea day and take lessons. Somewhere in the Fun times you will see "free gaming lessons" Attend a session. They let you learn without risking real money. Then you can go play at the $5 table and try your luck. Also I suggest you google "The wizard of odds" He has much better strategy guides available than what I could type here. You can also print out a "cheat sheet" card you can use in the casino to tell you what you should do in each situation. Do be afraid to use one. No one should mind. His website also has practice games available so you can try it out and learn before you go. most dealers on a cruise ship will help you learn if you just tell them you need help. They like tips.
The simplest way to remember the basic of basic strategy is to remember to hit until your total is 17 or more if the dealer has a 7 or higher showing. Always double down on 11 (first two cards) and always hit anything less than equal to 10. When the dealers card is 3-6 stay on 12 or higher. There are a lot of different possibilities but the what I wrote above will cover most cases.
For the tourney... they will have qualifying games all night. They track the 8 highest winning totals. At the end of the night those eight play a final round, the winner of which wins $500. You can re-enter the qualifiers as many times as you wish. I have found that you need a total of $5000 to have a decent shot at being in the final round (you start with $1000) So during qualifiers you are playing for a high enough total to "get on the board" of 8 highest. You play 8 hands of blackjack. Bet enough so that if you win you can get on the board. If you have $2000 left and 2 hands to go to get on the board you may have to bet it all each time to have a chance...
Hope that helps... It was a broad question... go visit the wizard and then you can come back and ask more questions.