Why would you use the speedbrake with thrust levers in a position other than idle in a descent? Besides stopping the aircraft from exceeding Mmo/Vmo of course.
During a VNAV PTH//SPD or LVL CHG descend, it is normal to have the autothrottle channel FMA announce ARM (after RETARD). You use the speedbrake to increase deceleration rate in a level segment, increase rate of an idle descent or help the aircraft decelerate faster at a fixed V/S (generally not more than 800 fpm below 250 kts).
As for callouts, it depends on the company. You may like it or not, but as long as those are in the OMB or whatever it is called over there in the US, you should stick to them. If you have a case against it, raise it to whoever is of concern. Where I work we don't have such callouts, we don't have "speed check and flaps X set" for the PM either.