That's under normal operation. All planes are certified to stop without any air reverse thrust[0] given they land at the right sized runway, right conditions, right position, etc etc.
But it's definitely part of the program.
They must also sit on the tarmac post heavy braking and the brakes must not burst into flames.
True, though I don't have a breakdown of net effects.
Commercial jet aircraft utilise thrust reversers, speed (or air) brakes (usually control surfaces which can extend out from the aircraft fuselage or wings), and landing gear brakes.
The latter are not insignificant, but thrust reversers and speed brakes are major contributors, especially immediately after touchdown.
There's also the effect of spoilers which increase the load over the gear and hence the braking capabilities of landing gear brakes.
Jeju 2216 failed to utilise nearly all of these mechanisms. It landed without flaps, spoilers, or gear, and possibly w/o thrust reversers.
If one divides weight of the airplane by the number of wheels it has, one would find one wheel carries around 10 times more weight than that of a truck. You even get a slightly better deal on landing when you don't have as much fuel.
That's a lot of weight but nothing crazy, so on a dry runway wheel brakes alone are more than enough to stop normally. They would also wear out a lot, overheat and occasionally ignite if used like that, so that's what thrust reversers are for.
