NEWBIE: What should I consider?

All,

Hello.  I am looking for advice from people on the ground or have recently worked out in Qatar. 

I am an IT contractor that normally contracts in the UK and EU through my own limited company.  I was asked if I was interested in a role in Doha by. a UK head hunting company and they put my CV forward to a local agency.  Now I have been asked for a skype interview for a role in Oil and Gas.  The role I am told is a six month project that is both offshore on the rigs and onshore in Doha.

Can someone give me a bit of a heads up and help me be a little less green:

What sort of stuff do I need to negotiate into a contract? 
What do I need to consider that I might not have thought of sitting in a rainy UK house?
What sort of stuff should I ask in the interview?

Thanks. for any responses in advance. 
Fox.