It means the same, yes.

It means "as long as". They will hold negotiations with the Iranians as long as the Iranians are serious in addressing the nuclear question. An example of use: They will be friends as long as/provided neither lie to each other.

It's a means to hide what is actually happening. So on the outside a factory may be said to be producing steel tubing for industry, when the reality is it's producing gun barrels.

1 - No difference 2 - yes, you can say both 3 - you can't say "let me check out it" but you can say "let me check it out".

It means they have had interviews with the applicant,and because of them, they must have gone well, they are offering him/her the job. To refer to something usually means to look at something and use the information found there to make a decision or pass on information (a book, an interview, a website etc). If I want to know something, I may refer to Wikipedia, or a textbook or I may conduct an experiment.

Not in the UK. I've heard of it but never heard it used in conversation.

At death's door.

Why I am so shy?

I'm really shy when I meet new people.  Maybe it's because I'm introverted and don't want too many people close to me.  Really, I'm happy with just a few. I also don't feel the need to get things off my chest with people I don't know. Maybe I've too many thoughts running through my head. That's why it's difficult practising English even though I'd like more foreign friends. I'm also too shy to use Skype to talk with strangers even though I like chatting.
So write to me if you want to exchange language tips. I can help you with your Russian and you can help me with my English. 
You can read a little about me in my previous note.

 

"Disbosom" - not too sure what this means Nadin, but I've made a guess.