Many students prefer to take a break after their bachelor's degree for a number of reasons, e.g., to travel, to earn money for graduate school, to gain work experience, or to take some time to clarify their career and academic goals before committing to a graduate program. Any one of these reasons is valid. Graduate schools accept students right out of undergraduate school as well as people who have not seen the inside of a university for fifteen years. It is more important that the "timing" of graduate school fit your career and personal time clock.
Yes. It is a good idea to contact the graduate admissions committee to find out how you can strengthen your application for the following year. Your candidacy for admissions will be considered anew, and your application will be reviewed and ranked on the merits of the new applications that are received for that year.
No. More often than not, your reasons for pursuing graduate study will be to gain further expertise in your undergraduate discipline, but it is not mandatory that you study the same discipline. In the case of Law, Social Work, Public Health, and Medicine, for example, there are no corresponding undergraduate disciplines. The entering graduate class will contain a wide variety of undergraduate majors and experiences. However, the graduate school may require you to take the core undergraduate courses within the discipline before considering your application.
Most people apply to somewhere between three and eight graduate schools, with five being the average number of applications submitted. Your preliminary research on graduate schools should give you an idea of the number of applications received versus the number of students accepted by each graduate school. This information will help you determine how many applications will give you the highest possibility of acceptance into a graduate program.
Most employers expect at least a two to three year commitment. If you know for sure you will be leaving within the year, you may wish to seek a more temporary position or consider other options for that year before graduate school.