You might have to play with the elevation a little bit, up or down some, and as far as the skew, yes if you are standing behind dish, and the dish is pointing east of your true south position (your longitude) it will be turned counter-clockwise, or a "- negative value".
If the lnb has no markings on it at all, nor the instructions cover that, sorry cant answer. Maybe a pic of it would help us figure it out.
If the lnb has no markings on it at all, nor the instructions cover that, sorry cant answer. Maybe a pic of it would help us figure it out.