Relatively quickly. Arthroscopic surgery typically allows a patient faster recovery and thus quicker return to work. However, recovery also depends on the findings of the surgery, any procedures performed during arthroscopy, and complications. Your type of work will also dictate if you can return to full duty (baseball pitcher will take longer than a secretary).
Depends on your job. Your recovery time will depend on what what kind of work you do and the type of surgery you have. For example, repair of a rotator cuff requires a longer recovery than a simple decompression (or removal of bone spurs). If you have a relatively sedentary office job, you probably can return to work within 1-2 weeks in most cases. If your job requires heavy liftiing, it will take much longer.