I've been studying the RFA and RDM usage guides and I still can't find answers to some questions.
References to the user guides and documentation would be very much appreciated.
As you are designing the dictionary handler for your app, please consider that you are connecting to the infrastructure (TREP or direct feed) that is supplying your data. RFA gives you an option of downloading the dictionaries from the infra, or loading the dictionaries from a local file. Downloading from infra should almost always be preferred, as it guarantees the correspondence between your dictionary and your data stream.
The dictionaries (field and enum) are per infra host you are connecting to, and if you are subscribing to multiple services from the same infra, the services will be under the same dictionaries.
One can open two sessions simultaneously, to different infras, which may be of different versions with different dictionaries. In this case the data from the session should be parsed with the appropriate dictionaries, downloaded from that infra.
If the dictionaries are uploaded from local files, it's the maintenance responsibility for the application admin to always keep the dictionaries in sync with the infra upstream.
The dictionaries with the identical version are the same.
It is customary to refer to SDK examples for info on working with the dictionaries, yes.