It seems that when someone calls a vote for a new map, a large percentage of people don't know what they're voting for. To help this it might be possible to give a preview of the new map, it would have to be configurable in the hud editor so as to not annoy those that play more often.
Sounds good! And when you have voted then the image should hide/dissapear. I really like your idea!
One of my suggestions was to make an info box appear whenever you hold your mouse over a map in the voting menu. This info box will give you info about the map (and possible things like user comments or ratings).
Another suggestion was for each map to multiple images that scroll across whenever you move your mouse over the top (again, in the voting menu).
I never thought about having a preview during gameplay and I like this idea. I definitely agree that it should be something each player can change in the HUD editor.