In either case, overrun combat allows only two fire rounds in which the Ogre cannot fire back . P. 35, first line. An Ogre which rams an equal-sized or smaller Ogre loses 3 tread units. When ramming units smaller than those listed, Ogres lose no tread units. This is a difference from the original Ogre boardgame, in which there is no overrun combat.
Smaller structures get no benefit from forests.
Any structure with a defense strength has that strength doubled in a town. Infantry move at normal speed in swamp, forest and towns. The defense value of a Secondary Battery should be 3. A GEV-PC is worth 6 points. When using miniature buildings which may have different defense numbers or structure points in different games, you can put a small sticker on the bottom showing the value for the current game.