What is the customer usually required by the people doing study to do for the study ? oneline , cable lenghts, cb , fuse cat # zfor transformers, what ?
What should we ask a company that says they do af studies since these people do repair work also ?

Look at a recent thread at:

http://forums.mikeholt.com/showthread.php/137714-Arc-flash-analysis

You really need to be careful. There are a lot of excellent people and companies performing very good studies but there are also people that probably should not be in the business and are going to get someone killed. I have heard many stories. The problem is the person specifying the study needs to be educated as to what they need.

There are a lot of good threads/posts at this forum to help you out such as:

Discussion of future standard for specifying studies
http://arcflashforum.com/showthread.php?t=1056&highlight=ieee+1584.1
http://arcflashforum.com/showthread.php?t=703&highlight=ieee+1584.1
http://arcflashforum.com/showthread.php?t=96&highlight=ieee+1584.1

Guide for Studies
http://arcflashforum.com/showthread.php?t=22&highlight=how+to+perform+an+arc+flash+study

In addition the forum host has a book on how to perform the studies coming out soon. It should provide a lot of good info as well.

Lots of good info here.