Comparing Counting Principle, Permutations, and Combinations

Question 1: If you have 10 people trying out for a board but only 5 can be chosen, would you use the counting principle, permutations, or combinations to solve this? The order they are selected to the board does not matter.

Question 2: You have 12 people trying out for 4 unique positions, president, vice president, treasurer, and secretary of a club. Would you use the counting principle, permutations, or combinations to solve this? The order they are selected matters in this case.

Question 3: You have 6 drinks, 5 entrees, and 4 desserts you can choose from for lunch. You pick one of each. Would you use the counting principle, permutations, or combinations to solve this?

Question 4: A game show contestant gets to pick 3 keys out of 20 to try and unlock a door. Does order matter in this case, and what should we use to figure out how many combinations of keys he could choose?

Question 5: How many ways can you order the first 3 letters of the word computer?