I am not certain about how 'salary man' is used, but 'white-collar worker' may be our equivalent. A white-collar worker is someone who works at a desk, or has a managerial job that traditionally would require that someone wear a white shirt and tie. (These days, the clothing is often much more casual.) Both men and women work at 'white-collar' jobs.I heard the word such as white-collar worker(s) standing for salary man you mentioned.
Probably not. Not all salaried employees are men who sell things or run companies. Some salaried employees are engineers. Other salaried employees are managers. Still others are police officers or soldiers. Of course, salaried employees can be men or women.In casual conversation, would 'businessman' be an appropriate substitute?