Where to look for a specialist to answer questions from visitors to the information site?

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Hello.
I plan to organize a service so that users ask a doctor (medical site) about their problems, and he answers them. Working directly with someone is very problematic. They can twist questions to themselves and constantly need to check everything. I’ll clarify right away that I need a person to come in every 1-3 days and answer questions, and not constantly work for me remotely.
I have several questions.
1) Where to look for a person for this kind of activity?
2) How to competently automate (or simplify) the process of paying for work?
3) Are there any sites that provide this type of service?
4) How to google on this topic?