Ok, a quick summary of the European regulatory environment.
The scope of EASARRs is Air Traffic Management (ATM). ATM is a combination of services/functions/facilities defined as 'The aggregation of ground based (comprising variously ATS, ASM, ATFM) and airborne functions required to ensure the safe and efficient movement of aircraft during all
appropriate phases of operations'.
Let's deal with each of these component parts of ATM. ATS is Air Traffic Services - Air Traffic Control (ATC) is one of these services, the others being Flight Information Service (FIS) and Alerting Service (usually abbreviated to ALR). These services are principally orientated around the instructions and advice passed to/from pilots by radio from the ground.
ASM is Airspace Management is a relatively new concept that revolves around making the finite resource of airspace available is the most efficient manner.
ATFM is Air Traffic Flow Management. This function regulates the flow of traffic at regional level with the objective of preventing overloading of the services/people in any particular area and optimising the capacity of the system. This function is now becoming known as Air Traffic Flow and Capacity Management (ATCFM) in recognition of the more recent use of this function to optimise system capacity.
There are another set of regulations that apply across the European region - the Single European Sky (SES) regulations. If your case study doesn't involve SES then it's best to ignore them. On the other hand, if SES is in your study there are additional things that you'll need to know....
As for the ESARRs, if you haven't already found it, there's information about them on the Eurocontrol website
here.