How it works just now, you buy the airstrike from a PT like you would a nuke/ion. You can't have both at one time. I believe they double in price when power plant is destroyed.
You right click to bring the binoculars up and left click to target. While painting an area, you are completely stationary and there is a visible beam from you to the target. Once fully targeted, both teams get an airstrike announcement (Although this is likely to change). There are a few seconds until the airstrike actually begins.
Airstrike do little damage to buildings, they're more effective against players. They aren't instant kill on higher tier vehicles or infantry so even if you are caught in a strike, you still have a brief time to escape the targeted area. As you can see here from one of my other videos, it took 4 shots from the Nod Airstrike to kill me over 4 seconds along with the medium tank.
From playing I can at least say that they've never really felt spammed or overpowered.