Eight of us go fourth, not back, to protect our king from an attack. What are we?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

Four people need to cross a rickety bridge at night. Unfortunately, they have only one torch and the bridge is too dangerous to cross without one. The bridge is only strong enough to support two people at a time. Not all people take the same time to cross the bridge. Times for each person: 1 min, 2 mins, 7 mins and 10 mins. What is the shortest time needed for all four of them to cross the bridge?

Do You See It?

As easy as you can get into me, it is as hard to get out of me.

Do you know what I am?

Spot what is wrong here in below Picture?

Find The Next Number in the series:

12 13 15 17 111 113 117 119 123 ?

In a kingdom, King George did not allow any citizen to visit the world outside. Also, only a person with proper paperwork was allowed to enter or he was sent back. A wooden bridge was what connected the kingdom to the world. The king had appointed a sharpshooter who would check the every five minutes on the bridge to check. After checking, he would go back to his hut and return exactly after five minutes again. The bridge took 9 minutes to cross.

A merchant was able to escape the kingdom without harming the shooter. How?

Can you solve below mathematical equation?

2^1234 - 2^1233

What work can one never finish?