Pay per case

I hope someone here can give me a little guidance. I have been offered a job to do some part time cm. This is for patients in a relatively large geographic area who would be receiving services in the home instead of a nursing home. I would help to coordinate these services intitially and monthly would call to check in on them. Every 90 days I would have to make a face to face visit. This is really more of a sw job, but they require a RN. I have done hh in the field so I know the pitfalls of being on the road. Now, I will be home-based for office work. They will supply me with a computer and a phone line. I will get a flat rate for each case. No mileage, etc. So, hypothetically, if I have 20 cases then I will be doing 20 visits in a 3 month period, 40 phone calls and will get the rate times 20. Am I understanding this correctly. What is a rate that I should be looking at? This is a rural area and we're probably talking a 75 mile radius with patients being pretty far spread out. Any advice is appreciated. I want to go in with my eyes wide open.

Ann