The answers to many of your questions about visa's, immigration processing fees, and interviews etc, may actually be found at the following link if you wish to look through it.
Embassy of the United States London, UK - Home
Hopefully that may help some of you that are looking for a particular piece of information. It is the official site, and on it you will also find links to both the US Department of State, and the USCIS. :)
Making yourself aware of the types of visa's or restrictions before you ask questions may help you to understand why people become unstuck on their visa's, or encounter problems.
It may also help you to get used to the forms, numbers, fees and processes that you will eventually need to negotiate your way around the complexities the US immigration.
Of course we really want you to post your questions and thoughts on the message boards, to help anyone else that is looking and to get feedback from our members that have been through the experience first hand.
All the best, and happy searching!