Vietnam and Korea.
Yes. In fact both countries had combat troops helping South Vietnam during the Vietnam war.
The countries that were actually "physically" involved, and were bombed or had US aircraft crash into them, whether they were "officially" in the war or not, were: Lao's, Cambodia, North Vietnam and South Vietnam.
The US during the American VN War.
The USSR and Red China.
US, New Zealand, Australia, South Korea, South Vietnam, Thailand, Philippines.
Vietnam was split into two countries during the vietnam war, the north was ruled by Ho Chi Minh and the South by Ngo Diem.
The countries that were independent durning the European Colonization in Africa was Liberia and Ethiopia
Washington was at war with Hanoi.
ROK (Republic of South Korea); Philippines, Thailand, US, New Zealand, Australia, South Vietnam.
Yes. A number of European countries are neutral and were neutral during conflicts such as World War II. Ireland, Sweden and Switzerland are three such countries, and there are others.
During the Vietnam War, all combatants (including North Vietnam) used draftees except for the New Zealanders, they sent volunteers to South Vietnam.