The headsets we use as a standard on our frames.

You can have the cables which go to derailleurs and rear disc brake integrated. They will enter the frame just below your stem. This looks neat, but gives a bit more work when you need to service your bike or want to adjust your handlebar. The choice is yours.

A headset comes with a expander and Raamwerk topcap

Evidently, you can order bearings per one, to function as a replacement, in the event of a worn bearing.