Bill Tindall
I would have thought this topic would have been covered by Curtis. He sticks the ends of his tenons in hot sand for a while. It has been a long time since I watched him do this part so I don't remember the time, but it should be quick and the hot dried wood takes on different desirable properties after this hot treatment.

The rest of your questions can not be answered for lack of data. Drying rate depends most on temperature, air circulation and humidity of hot air. At 200 degrees with good air circulation a spindle would be dried in an hour or less.

The cooking store will have a suitable scale. Drying to constant weight is no more than that. The wood has reached as dry as it will get......for the conditions used. Without knowing the humidity for these conditions the moisture content of the wood can not be predicted.