Salve,
I met the photos of the Mithreums that were recreated. However, all of them were recreated as part of some historical exposition, in other words, they were not operating mitreums - religion place, but rather a reconstruction for historical clarity. However, it's worth mentioning that I saw a photo of the Mithreum, which was made in the bustle of the house, nevertheless, I would not say that it was correctly recreated, this Mithreum was more like a room - a setting for role-playing games, rather than a historically authentic one Mithreum.
Concerning the second question. Here everything is quite simple. Mitreums around the world are fairly well researched and studied, so it's enough just to understand the available scientific material. For example, one of the articles:
http://www.tertullian.org/rpearse/mithr ... ge=cimrm34Vale!