Removing quarter panels involves drilling out many spot welds, at every edge of the panel(s). Where the quarter joins the roof the seam is leaded. You can melt out the lead and then drill the spot welds there as well. At the front A-pillars are similar joints close to the top of the pillar if I recall correctly. Many people make their own cuts depending on what they are trying to replace, but separating at the factory seams is the preferred/best way IMO.
Hope this helps.
Regards,
Bob