I don't know where you can find information about the job requirements on the web but I can at least give you an idea as to what some of the different roles can be defined as.
EDI Coordinator/Project Manager:
Typically a manager of sorts who is required to report to upper management about new projects and current timelines. Usually acts as a Project Manager by defining scope, business requirements, and general management of employees/consultants.
EDI Analyst:
Usually does the grunt work that the EDI Coordinator/Project Manager doles out. Responsible for EDI design, interface design, documentation, gap analysis, and detailed business requirements. Can act as EDI mapper, implementor, partner setup, document flow and system design.
EDI Programmer:
Usually involved in the EDI mapping but mainly involved with writing custom interfaces between EDI system and application system (such as the database). Most often not used to work directly with customer. Usually involved with the EDI design.
EDI Manager:
Usually not too involved with the day to day of EDI but has experience in all aspects of the EDI life cycle (from EDI design to application system knowledge). Doesn't usually do the work but offers MANAGEMENT insight.
Hope this gives you an idea.