We recommend customizing the appearance of Tersus applications using CSS. See http://www.tersus.com/#Tag=CSS & specifically for mobile apps, http://www.tersus.com/#Id=3288.
However, certain properties such as width and height can be set through specific properties as you describe, and this should work for mobile templates as well. I've compared Display/Image to Mobile/Image and found that both support the properties you mentioned, except that the Mobile template requires that you specify a unit of measurement (px, em, etc.) whereas the Display version does not require it, and assumes px if not specified.
For best results, use the Firefox browser..