I am getting ready to do an addition to my home that will consist of a master bedroom and bath. I figure the more time spent planning the smoother the execution and the more people I speak with the better my plan gets. So I have a couple of questions:

1) Since I will be adding a bath, I want to decommision one of the existing bathrooms consisting of a toilet, sink, and bathtub. Bearing in mind that the house is on a slab, and the wall in which the DWV currently runs will in all likelyhood cease to exist what is the proper way to accomplish this decommisioning?

2)I have located the 3" vent stack about 7' away from where I would like to place the washing machine discharge and laundry tub/sink. The stack goes straight from somewhere below the slab through the roof. My thoughts are to open the area up around the stack to find a good place to insert a tee that would allow me to connect the 2" drain line coming from the washing machine / sink. The plan is to cut through the slab to run the 2" drain line. I want to have the sink and washing machine connect to the 2" drain. I would run the vent for the drain up through the ceiling into the attic where I would connect the vent back into the 3" vent stack.

My other (and least perferred) option would be to run the drain inside the interior wall to just before the exterior of the house, bust down through the slab and then through the stem wall and make the connection outside by digging up the waste line. Either way looks like a lot of work. Appreciate any ideas, comments or feedback.