Shimano is the only major manufacturer to stick rigidly to cup & cone bearings. If you have the time and ability to keep these maintained, they will go on for ever.
<laughs a lot>
No.
I've had to replace the cones on several of my wheels. Pitting and a worn groove after maybe 10k miles. Bearings kept properly greased and seals hadn't failed.
Cup & cone bearings will fail like this if they are adjusted too tightly.
Tightening the QR will make enough of a difference that a wheel that seems correct off the bike will have bearings that are too tight when on the bike. You have to set the bearings with a small amount of play, so that it just disappears when you put the wheel in the bike.