Hello Milena,
Adjoining parts of land means they lived in a close community. That was comon in the old days. I dont know which Croatian genealogist you are talking with but it is not 100% possible to determine an ethnic background through a surname.
The Dalmatia area is/was primarly inhabited by ethnic Serbs, although after the last war thing demography has changed here and there. I have archival documents from Dubrovnik here, when I have time I will see if the surname is mentioned in it. You should know that the whole of Dalmatia has been hit heavily during the last war, there are not many archival sources as we want to and many people from that region have a hard time finding their ancestry.
As for the different religions. That could be anything, Serbs e.g. are both Orthodox and Catholic and before WWII there was virtually no emphasys on this.
