Rome was already leading power during the Republic. Levant was under control of Roman empire for 100 years at the time of Jesus. While Greeks was the most dominant language in Roman empire through its history, it was never language of the majority. There was 18-20 millions of Greek speakers in Roman Empire while the Empire in the peak had 80 million people. Rome as city dominated the empire and the Roman emperors dictated the fashion. When empress changed her hairstyle, so did every free women from Britain to Judea. Picture of the emperors were all over the empire as official documents had to be signed under "Imperial" presence. Caligula was big admirer of Egyptian pharaoh lifestyle (maybe reason why he was sexually active with his sister) and wanted to move his court to Alexandria. Either way during his reign, men kept their hair short or shaved, because he was balding. It was his big handicap and he was ashamed of it.
Paul was a Roman citizen, therefore, he followed legislative proceedings and benefits of the Roman world, which included Roman citizenship. This was Latin benefit, and had nothing to do with Greeks. Greeks were regularly enslaved and sold as a cattle on slave markets all over the Roman empire. Paul would have not much to gain from being Greek speaking in the position of the Imperial court where he appealed.
"Sexual issues? Well, he's talking to people who live in the land of the orgy"
People are too much affected by viewing the movie Caligula and gossip courts stories, and subsequent Christian ascetics, but generally, Roman society was very conservative. Even on the matter of sex subject. While sex was available, so did prostitution, same-sex relationships, free attitude, we cannot talk about sex as open in Roman time in our post 1960's sexual revolution. Romans would not even kiss in public as it was not recommended since the time of Augustus. Commodus was ridiculed for kissing his favorite boy-toy in public, and Severus criticized for showing affection to his wife Julia Domna.
Either way, it is not possible to separate Paul from Roman citizenship. He was born with it and it was still very rare in his lifetime for non-Latin subjects. Emperor Caracalla expanded in 212, but in 50AD we can estimate about 7 million of Roman citizens in the empire, most of them in Italy.