Inertial confinement doesnt produce a "stable reaction" it is pulsed by it's nature, think of it in the same way as a single cylinder internal combustion engine, periodic explosions which are harnessed to do useful work. So no the laser energy is required every single time to detonate the fuel pellet.

NIF isnt really interested in fusion for power production, it's a weapons research facility that occasionally puts out puff pieces to make it seem like it has civilian applications.

In my experience the community will usually distinguished between "scientific Q" and "wall plug Q" when discussing fusion power gain. Scientific is simply the ratio of power in vs power out, whereas wall plug includes all the power required to support scientific Q. Obviously the difference isn't always clearly delineated or reported when talking to journalists...

If you haven't already seen the talk recently given at the Chaos Computer Club's "Hacker Hotel" named "How Thermonuclear fusion works, free energy without waste", I highly recommend it. https://libranet.de/display/0b6b25a8-ff152736-e38872dd7aed088e