Sure, flip the screen 180 degrees. Sorry but there's no way I have seen posted. On the usability front, it is not something I have seen anywhere and the usual advice is not to go against established conventions. That however is your call.
See www.grainge.org for RoboHelp and Authoring tips
That's the answer I suspected (but not the one I hoped for). For what it's worth, I agree with your advice about sticking with conventions but this is one of those outside cases where the other way makes sense. I have an image inside a frame that's at the bottom of a window. In this case, dropping down works but "dropping up" would probably look better.
It's a bit more complicated. Rh adds the drop down text as a div below the paragraph that holds the hyperlink. It then simply shows or hides the text. You must therefore play around with css positioning to get this to work (not recommended), or you must move the location of the drop down text holder above the current paragraph either manual or with a script.
Unless you want the drop down content to appear as an overlay or a pop-up. In that case you need to rewrite quite a bit of the underlying code of the drop-down.