1. If the above is the unit indicated on his separation certificate it's merely the unit he was assigned to at the time of his release from active duty and may or may not have been the unit he served with overseas.
2. The Bronze Star is awarded for "heroic or meritorious achievement" in actual combat OR in direct support of combat operations. Also awarded for meritorious achievement during peacetime (although not quite as extensively since advent of the Meritorious Service Medal in 1969). Combat award is signified by a small (1/4") bronze letter "V" worn on the service and suspension ribbon of the decoration.
3. The citation, even if you could locate a copy, would probably reveal little or nothing beyond the date of the action. These typically read simply, ". . . for heroic (or meritorious) achievement during the action at * * * * * on (date of action)." Sometimes the country would be named but the exact locale was almost always omitted in the manner shown. Citations were deliberately vague, mainly for security reasons.