Primary fire can be dumbfire rockets, and secondary fire can be seeker rockets
Machine guns on the tanks would make them too powerful, because they would be able to take on most units, including aircraft, easily.
Placing beacons isn't too hard if you know where to do it and remember to guard it with your life. I do it 9 out of 10 games
Though more realistic, the machine gun turrent on the chinook is a bad idea. If you could have a chinook with a machine gun, why get an orca or an apache? It would mess up the balance.