18. In fact, 16 questions are enough (and this is not the minimum).

In the first four questions, we will find a knight. We will do this as follows: ask the first and second residents about the third. If both answered that he is a knight, then he is a knight (otherwise, all three are liars, which is impossible).

If not, then ask the fourth and fifth residents about the sixth. If someone here said that he is a liar, then among $1,2,3$ there is a liar and among $4,5,6$ there is a liar, so the remaining 59 residents are knights, and the remaining questions will definitely be enough. Otherwise, the sixth is a knight.

The remaining questions will be asked to the found knight about the other 64 residents. Using dichotomy, we will find one liar in 6 questions, and in the next 6 questions - another one.
18. Among 65 residents of the village, two are tricksters, and the rest are knights. A knight always tells the truth, while a trickster can either tell the truth or lie. You can show any resident a list of a group of residents (including a group of one person) and ask if they are all knights. How can you find both tricksters by asking no more than 30 questions?