use the avenger vehicle in mass if u r playing as the US. it can shoot down missiles including the scud missiles.

Press and hold the Ctrl key and click on the location you wish to attack (It's called force fire command and is a standard feature in many RTS games, you can even fire on your own units and buildings this way.).

It's possible to assign units (single units or groups of units) or buildings to the number keys of the computer keyboard (assign: select unit, unit group or building, then press and hold Ctrl and simultaneously press the desired number, select: press number, pressing twice will jump to the unit's/building's position on the map).