You should start with identifying the original spelling of the surnames you are researching:
MEDIGOVIĆ / МЕДИГОВИЋ
RAĐENOVIĆ / РАЂЕНОВИЋ
MEDIGOVIĆ family from Petrovac, Montenegro, are identified in records of the Serbian Trade Association as coming from the smaller village ŽUKOVICA, PETROVAC:http://baza.privrednik.net/privrednik.php?find=Medigovi%C4%8...http://www.rodoslovlje.com/en/documentation/serbian-trade-as...
The middle name for everyone you listed is the first name of the father.
Important thing to keep in mind is that the difference between what is available in English and what is available in local languages - your best bet for successful research is to locate a descendant of the same family or clan who can communicate in English and share their knowledge with you, both from the oral family history tradition and the written sources.
Serbian Genealogy Society SGS "Rodoslovlje"http://www.rodoslovlje.com/en