Keyboard words are not in alphabetical order, Why?

There are people and strange monkeys on this island, and you can not tell who is who (Edit: until you understand what they said - see below). They speak either only the truth or only lies.
Who are the following two guys?
A: B is a lying monkey. I am human.
B: A is telling the truth.

You have a 12 liters jug full of water. You have two empty 8 liters and 5 liters jug. How can you divide the water into two equal parts using these jugs?

Replace the question mark with the correct number below.

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

I know a country, If you remove the last alphabet of its name, it will become a part of your body. Do you name it?

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?

The owner of a popular clothing store comes up with his own method of pricing items. A vest costs $8, socks cost $10, a tie costs $6, and a blouse costs $12. Using the owner’s method, how much would a pair of underwear cost?

If Bihan is 10, Anirudha is 20, and Kim and Seal are both 5, but Rikold is 10, how much is Kenniger by the same trend?

Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.