[nradov]

All carrier aircraft are typically brought into the hangar for several hours of maintenance after every flight. But if necessary the F-35B can be immediately refueled and rearmed on the flight deck and sent right out again in a matter of minutes.

Maintainers on a carrier can do fairly complex repairs, including engine replacement. If they need more working space in the hangar then other aircraft can be parked temporarily on the flight deck.

The F-35 is primarily a strike fighter so supersonic speed isn't that useful. The biggest problem with flying at supersonic speeds is it drastically increases fuel consumption, and the F-35B has a very limited fuel capacity. British carriers have no tankers.

As long as an aircraft is still in active production the design phase is never "finished". Updates will continue for decades. The F-15 design is about 50 years old and it's still not finished.

The F-22 production program was cancelled in 2011 because there was just no funding available. It wasn't possible to fight the wars in the Middle East, and procure more F-22s. Something had to give.