Four jaw chuck is used to hold cylindrical rough casting for turning.
Exactly at centre height of the workpiece with tool axis perpendicular to the workpiece axis
Exactly at centre height of the workpiece with tool axis perpendicular to the workpiece axis is the correct position of threading tool to cut V-thread.
Arbor is not a part of centre lathe.
Left-hand end of the lathe bed
The headstock of a lathe is situated at the left-hand of the lathe bed.
The horizontal feed, cross feed and screw cutting movement in a lathe is controlled by apron.