For someone that is 177 lbs I would expect that there would be several thousand cc's of fat to be removed, but it would depend on your fat distribution. 650 cc does not seem like a lot.
What temporary effect your garment has on the buttocks will have no effect on the long-term outcome. At your pointing convalescence there still swelling which can fluctuate in response to the pressure generated by the garment.
It is never safe to take ecstasy. Period. Please advise your plastic surgeon of your decision so they can decide if/how to proceed with your surgery.