Know how many employees you will be serving and who is your helper or backup support.
Know if there is a Union. If there is one, most of the time, they can be a challenge to work with. You will have to work around the Union.
Know if you will be doing workmen compensation, FMLA, or any other medical leave or if the company has another department or outsources for this. If you are the only one responsible for this you will have your hands full on top of the other responsibilities you have.
Find out if you have a Medical Assistant to help with employee appointment scheduling or else you will be by yourself answering phones and doing clerical tasks.
Find out if you have team meetings with other health, safety, and environmental professionals. Communication and teamwork are extremely important.
Hope this helps. Best of luck to you.
Being a "one man show" is not the answer. Being part of a team is!