Hi,

1) You do not need to.  The "Click here" text only shows in the edit view,
not in the slide show view

2) You can use the correct layout to eliminate unwanted placeholders.  With
the slide selected, click on Format => Slide Layout => and select the
appropriate choice from the graphical display.

3) You can select the entire placeholder text box (click in the box  then
hit escape, notice the text box boarder will change to indicate the box is
selected) then hit the delete key.