Short answers, pulled from the story.
The name Mercury connects to the Latin word merx meaning merchandise and links to the Proto-Indo-European root mergh for boundary or border. This linguistic thread suggests a role as keeper of boundaries between worlds.
Construction finished on the 15th of May 495 BC within the Circus Maximus. The location sat between the Aventine Hill and Palatine Hill during disturbances between patrician senators and plebeians.
Romans interpreted Celtic gods like Lugus as local manifestations of their own pantheon while Germanic tribes viewed Wotan through the lens of Roman Mercury. Tacitus identified Wotan as the chief god of Germanic peoples in the 1st century AD and this association survives today in English Wednesday and French Mercredi.
His major festival occurred annually on the 15th of May known as Mercuralia. Merchants sprinkled water from his sacred well near Porta Capena on their heads to mark commercial success and abundance in Gaul where he was particularly revered.
Virgil's Aeneid features Mercury reminding Aeneas of his mission to found Rome while Ovid's Fasti assigns Mercury to escort nymph Larunda to the underworld. These narratives highlight his role as psychopomp leading souls to afterlife and his functions expanded beyond simple trade into divination and eloquence.
The United States issued a Mercury dime from 1916 to 1945 featuring Winged Liberty. Despite wearing a Phrygian cap instead of winged helm the coin bears his name due to resemblance.