Technically, professional does not mean excellent, or that it's your life, it mean paid.
You can't be a professional volunteer or blood donor.
Yes. Only if done regularly. Like if the best person always does things for free and has never made a paid career out of it, he is technically an amateur. If the sucky guy is paid to do it, then he is a professional.
The job may be professional grade, but if it's not his job, then he is still an amateur.