I think powerpoint is horrible and unfortunately the openoffice Impress “clone” has failed by copying all the “features” from Microsoft.
Instead I suggest using the Draw package. It is fantastic! You can achieve exactly the same that you want with Impress, but with a much higher degree of freedom. Potentially you need some more hands on when scaling text back and forth and adding bullets, etc., but its worth it.
You can define your master pages here too and invoke them by (on the page)
Right Mouse Button > Page > Slide Design ...
Then pick your master page of choice.
Also use the different styles for all kinds of things, arrows, text, etc.