I'm with Joefin. Tell the professionals when you are interviewing them that you can't have
any dust. Stay and watch/help them. Walts idea about the room or extra tarps will help, too.
Don't go with the cheapest bid either. The best guys will know what to watch for. If they are cutting and the wall starts to collapse? or crack where it isn't supposed to? They will have supports or something to keep it from crashing down.
When you saw into the re-bar what will that do to the blade? Is there special precautions to take to prevent landslide?
An 8" wall is pretty serious. I saw a storm cellar years ago that was done by some contractors and when they started to move the forms for the entrance opening it caved in. Where the re-bar was placed or not placed didn't allow for the opening to be there.
You'll probably have to put in a steel frame surround to support the area.(You probably already know)
ARB, I don't want to sound like a know it all. I just don't want you to get hurt, or have something collapse and know that I didn'y say anything.
After talking to a contractor about how they will go about it,you might get enough info to do it yourself.
Good luck and let us know what you do.
JAckal