1st off when measuring how long to cut for your borders, measure from the middle of your quilt as the edges might have gotten stretched and you'll end up with wavy borders if measured from the edges. 2nd most times the sides go on 1st then the top and bottom and again you'll measure from the center of the quilt or at least measure from the center and again on the edges and then average it out. I measure from the center only and normally have issues with wavy borders. I cut each border and attach when I am adding multiple borders unless I'm doing them mitered style, then I might stitch all the borders for each side/top/bottom together and then attach but you have to allow for extra length so you can miter the corners. I rarely miter my borders unless I'm using a striped fabric and want the stripes to meet up correctly. The adding .5 for seams, well if you think about it the outer .25 seam will be encased with the binding so you're really not losing that measurement at all. Just my thought on this subject.