Not really. Troop is just another way of saying Soldier. When you're in the Army and your Commander wants you, he'll sometimes say, "C'mere Troop!" it's just another way of saying Soldier(s)...
They are to lazy to figure out if they are soldiers or Marines, sailors, or airmen, so they say "troops". I read this article too. They were not a unit.
Like they said, Troop is just a generic term to reference a member of the military.
For the second question, a troop is only a "unit" of people in Army Cavalry units. For example, instead of Alpha Company they would be called Alpha Troop.
