I really don't know the answers to all of these questions, but I'm sure the employer must hold your job. There is a nominal pay for being a juror, I think something like $40. per day.
The judge today said that the ONLY people who didn't have to serve were convicted unpardoned felons, those unable to speak, read or write English, those over 70, and those with medical conditions that wouldn't allow them to serve.
I have heard that people with certain occupations are not called, including teachers and doctors.
DonM