Logic Riddle

Question: What are the next two letters in the following series and why? WATNTLITFS__

Question: At low tide 14 rungs of a ship are above the water, the rungs are 15 centimeters apart. each 15 mins the water rises 15 centimeters. after 2 hours and 30 mins how many rungs are above the water?

Question: During what month do people sleep the least?

Question: When is 99 more than 100?

Question: When you're given one, you'll have either two or none?

Question: A horse jumps over a castle and lands on a man, then the man disappears. How was this possible?