The most important benefit is not credit, it is the learning, improved skills and real-world experience you get. No, although many employers are interested in the students they believe will stay with the company. After all, part of the reason many companies or organizations participate is to help identify and train future employees. It depends on the employer. Smaller businesses are less likely to have other students, but they offer a great opportunity to learn a lot about the enterprise.
Many larger companies employ multiple students each term.
Regardless of whether or not there are other students there, good college programs approve work positions that will provide productive tasks and supervision for students. You will talk with your co-op coordinator to help you decide. Colleges have information on work sites in a variety of locations. If you are thinking about a more distant location, they can often help with information about places students have worked before. Some employers assist with the travel and living arrangements for distant locations.