Here are some of the answers to your questions.
This exam is specifically designed for the Installation, configuration and deployment of Windows 7 Operating system. This is entry level of an EXAM. And it is designed to show some familiarity with the operating system operations and functions.
Who should give this exam?
Anyone who wishes to demonstrate his skills in delivering the operating system in the work environment. This exam definitely helps you establish in the networking job market. Most likely these exams are given by desktop support engineer or the networking engineers.
The exam costs 3350 plus taxes depending on which center you're giving. The cost may go upto 4000 as there are local taxes and professional taxes added into it. If you go directly to Microsoft certified exam centers, you can schedule the exam with less taxes.
Most of the content for this exam is available on Microsoft community forums, Microsoft book store and the reference links given in the exam description. You may also find the test related information and sample tests around on internet.
You may get more information on the Exam 70-680 here : https://www.microsoft.com/en-in/learning/exam-70-680.aspx