Have you seen Brief History of St. John Chrysostom Albanian Orthodox Church & SS. Peter and Paul Church, Uniondale PA? Dedicated church cemeteries seem to have been the norm, but they also used sections within larger non-denominational cemeteries.
Which congregation an immigrant joined often depended on what was convenient for worship. Slight differences in church custom and liturgy between various national churches could be overcome if there weren't enough of a specfic group in a city or a neighbourhood to sustain a parish.