Yes. A pro shop or authorized retailer can order one through Titleist with the adapter installed of you can find a used one through multiple sources.

Correct. Many shafts on eBay may have an aftermarket SureFit adapter that may or may not be as accurate or reliable as the Titleist

There are shops that sell driver shafts. Unless they pull one from a real deal Titleist shaft, they have to use the aftermarket adapter.

The adapter is different on fairways and hybrids. All Titleist drivers from 910 to now can interchange driver shafts. One option is to buy a used Titleist driver and swap shafts. Then resell the used driver with your old shaft. Definitely for the 917 drivers and for some TS drivers, the used unit may be less expensive than getting a new shaft.