It seems that you are well prepared, although the material to provide depends upon your particular circumstances. As a general rule, you want to provide as much documentation as possible establishing your ties with Romania.
One item that you did not list is a letter from your employer stating that you will be returning to your job after your trip to the US. You could also take pay slips for as far back as possible to establish your work history.
Attorney Edward Weiner
http://www.immigration-aux-usa.com