True, if the ref warned or not you have to wait for the score to be called.

False - Rule. 14.D.4.b. Instruct players on the need to wait for the referee to call out the score before serving or a FAULT will incur.(Not a techincal foul!!)

Serving before the score is called is a fault and will result in a service change or a side out.

True

Not waiting for the referee to call the score, is a technical foul. A warning is normally issued to make the player aware of this and if the violation continues, a point is awarded to the non serving team and they switch courts.