In reply to your question: "according to what rules did the Greeks adopt foreign names to their own language.":
Although the Greeks before christianity were using just a few foreign names among the over 28000 names of Greek origin (
www.lgpn.ox.ac.uk), that changed dramatically after their conversion to christianity, when they had to start using foreign, mainly hebrew, names.
This is because of a 4th century AD law of the
Christian Orthodox church of the eastern
Roman Empire, (known as "Byzantine Empire"), according to which every baby must get baptized to christianity, in order for the Greeks to start using only biblical or
Christian names, facing heavy punishments if not done so. The law ("Neara 116"), was part of a group of laws used by the Christians until 10th century AD to force the Greeks to lose their "Hellenism" and become Christians.
Unfortunately that law is still in use in Greece, luckily without the punishment… :)
References: Trombley
Frank R.: "Hellenic Religion and Christianization, 370-529", Vol. 1, Leiden, 1993
Jaeger
Werner: "Early Christianity and Greek Paideia", N.Y., 1961
Pharr C. "The Theodosian Code", Princeton, 1952
Boyd William K.: "The Eclesiastical Edicts of The Theodosian Code", N.Y., 1905
Krueger
Paul: "Corpus
Juris Civilis. Codex Justinianus",
Berlin, 1954
Adeney
Walter: "The Greek and Eastern Churches" N.Y., 1928
Baron d'Holback
Paul Heinrich Dietrich: "Christianity Unveiled",
London, 1819
Baur F.C.: "The Church History of the first Three Centuries"
London, 1878
Chuvin
Pierre: "A Chronicle of the Last Pagans", N.Y.,1990
Ellerbe
Helen: "The Dark Side of
Christian History",
San Rafael CA, 1995
Fletcher Richard: "The Conversion of Europe. From Paganism to Christianity, 371-1386 AD",
London, 1997
Haught
James A.: "
Holly Horrors", Buffalo, 1990
Vlassis Rassias: "A...
Love story. (History of
Christian Override)", Athens, 2005