I'm not sure what you mean by the bolt welded - that's really odd. The only elliptical bolts should be on the front lower control arms, and on the rear tie rod arm.
About the negative camber: Mercedes specs state that up to negative 4 (yes, FOUR) degrees is OK in the rear. Up front you should be able to dial it down to negative 1 or so. You do want some negaitve camber if you corner hard. If you don't, then you want it closer to zero. The problem is the kits to correct this are VERY expensive.
Scroll to the end of this PDF for the data on the alignment specs:
http://www.meimann.com/docs/mercedes/AMG_wheel_install_02.pdf
Regards,