Short answers, pulled from the story.
Scholars have struggled for decades to explain the name Oceanus with no single theory convincing all experts. M. L. West described its etymology as obscure and impossible to derive from Greek itself while Pherecydes of Syros suggested it might be a loanword. Some researchers point to Semitic roots or an Aegean Pre-Greek non-Indo-European substrate proposed by R. S. P. Beekes.
Oceanus was the eldest son born to Uranus and Gaia according to Hesiod. He married his sister Tethys and became father to thousands of river gods including three thousand neat-ankled daughters known as Oceanids. Homer named twenty-five specific river gods such as Nilus Alpheus Eridanos and Strymon.
Oceanus did not join the attack on Uranus when Cronus overthrew his father and ultimately stayed neutral during the great war. Apollodorus stated all Titans except Oceanus attacked Uranus while Proclus quoted an Orphic poem showing angry Oceanus brooding whether to join Cronus. Afterward Oceanus remained free while others were imprisoned in Tartarus.
Hesiod called Oceanus perfect river flowing back into itself around earth while Homer referred to stream of river Oceanus bounding the Earth. Roman geographer Pomponius Mela said inhabited earth entirely surrounded by Ocean receiving four seas including Caspian Sea Persian Gulf Arabian Gulf and Mediterranean Sea. Julius Caesar used this term for Atlantic Ocean and Herodotus rejected reasoning claiming summerly Nile flood caused by connection to mighty Oceanus.
Sophilos painted Oceanus on early sixth century BC Attic black-figure Erskine dinos with bull horns adorning his head while left hand held snake right hand fish. Body from waist down resembled fish closely followed Tethys Eileithyia Hephaestus mule ending procession. Hellenistic Roman mosaics often depicted upper body muscular man long beard horns claws crab lower body serpent Typhon style cosmography continued represent encircling equatorial stream much like Achilles shield.