What 4-letter word can be written forward, backward or upside down, and can still be read from left to right?

In the picture given below, can you find out which digit will take place of the question mark?

We have arranged an array of numbers below. What you have to do is use any kind of mathematical symbol you know excluding any symbol that contains a number like cube root. You can use any amount of symbols but you have to come up with a valid equation for all of them.

0 0 0 = 6
1 1 1 = 6
2 + 2 + 2 = 6
3 3 3 = 6
4 4 4 = 6
5 5 5 = 6
6 6 6 = 6
7 7 7 = 6
8 8 8 = 6
9 9 9 = 6

My location can be determined by the below rebus.
So where am i ?

Can you find a number that lies one third of the distance between 1/3 and 2/3?

What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps?

If we change the South-East direction into North and North-East into West and all others similarly.
Can you find out which direction will be in the place of South-West direction?

Do you know who was buried in John's tomb?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

To attend world science seminar, A famous chemist from Mexico visit
London. In the lab, the scientist was killed and his six assistants were under suspicion of killing the chemist.
Name of six assistants: Austin, Wayne, Dege, Oscaru, Lingard, and Rojo.
He left a note "76-20-44 79-16-22-7"

A local detective Jack was called to solve the case,

After reading the note, Jack instantly asked the police to arrest the murderers.

Who are the murderers?