As for wax build up this is usually easilly removed by using an old toothbrush.
if you use a high quality wax and apply a thin coat going with the edge of the film...one should not have any wax build up. if one uses turtle wax or it's equivalent...wax build up will be a problem for any cracks, emblems or seams. i use zymol "concours" and haven't had any problems with this.