Blocking a window in place

I am replacing some old windows with new larger windows. What is the best way to remove stucco for the new rough opening? I was told before to use a diamond blade on a circular saw, but I noticed a contractor at a neighbor's house using an air chisel for this purpose. I also heard that using a circular saw may not be the best because it is better to have a jagged edge instead of a straight line where the old stucco meets the new stucco (because cracks tend to form along the straight line). Also, I heard that you have to be careful to not destroy the wire in the old stucco because the new wire needs to tie into it. Can you confirm. Thanks for your help.

I want to 'turn' the door knob so that the door locks from the outside rather than the inside. I know it can be done as we had someone do one for us but in this case I'll have to try to do it myself. I'm definately not a handy person and would need simple step by step instructions. :o Is there someone out there who can help me?