Dropping a column: In pre V16 you could be in table edit and drag the column closed to "Hide" it, however, with V16 drag the column until it notes 0.0 in the yellow size box. Hide, per se, is gone.
Development is aware of the page number issue
Window placement: All I can say here is it relates to the Java interface. In V15 & before the output viewer, can I say, controlled the placement of the various screens (data, syntax, ...), whereas in V16 this all changed and they are "independent" so, no, can't make 1 supersede another. This is both good and bad as you continue learning V16.