Can not understand these three sentences, help

[japanjapan]

Dear teachers,

Please read the following sentences:

No.1
Today's popular feelings of insecurity often resemble an obsession.
"As a result of our fear," says one major study of American attitudes
toward crime, "we may soon be living in armed fortresses -- both at home and within ourselves. "

I don't understand the red part. What does it mean?

No.2
Three quarters of the world's mail, including telexes and cables, is in English.

I looked up these two words in dictionary, but it seemed to me there was no difference. They must be different since they are two words,what is the difference?

No.3
He has promised to help me as far as he can.

Does this sentence make sense? I suspect it should be "as far as he can go".
But the sentence was printed in a book. Can we really say "as far as he can"?
it sounds weird to me because there is no verb. Help me out.

Thanks a lot.
yours sincerely

[Abdo]

Dear Japanjapan
Here are my answers to your questions:
Question 1. within ourselves
Within ourselves here means that we may have fear inside us or some kind of fobia.

Question 2. cable = (in the past) a message sent by electric signal
Telex = a message sent by a telex machine (a machine that uses a telephone line to send message.
(Cambridge International Dictionary of English)

Question 3. He has promised to help me as far as he can.
This sentence means: He has promised to help me as far as he can (help me).
Abdo